BNL Home
September 2018
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  1. Nuclear Physics Seminar

    11 am, Small Seminar Room, Bldg. 510

    Hosted by: Jin Huang

    Most of elements heavier than Fe in the Universe are produced by a series of neutron capture reaction and ??-decay in stars. The s-process, which occurs under moderate neutron environments (~107-10 neutrons/cm3) such as in He burning of massive stars, is responsible for producing almost half of the heavy elements. Neutrons for the s-process environment is believed to be supplied by two dominant reactions, one of which is 22Ne(?,n)25Mg reaction. This reaction in massive stars is dominated by a few resonance reactions. Nevertheless, there remain large uncertainties about contribution of the reaction to the s-process nucleosynthesis because the reaction cross sections are too small for direct measurements due to Coulomb barrier (E? = 400-900 keV in the lab system). In the first half of this seminar, I will present our experiment to determine these resonance strengths with a cyclotron accelerator at Texas A&M University. The experiment was performed by an indirect approach using 6Li(22Ne,25Mg+n)d ?-transfer reaction, in which resonance properties such as neutron decay branching ratios of produced 26Mg were studied by measuring deuterons, ?-ray, and 26Mg in coincidence using large arrays of Si and Ge, and a magnetic spectrometer. Our results showed neutron production from 22Ne(?,n)25Mg reaction can be about 10 times lower than past measurements. The effect of our measurements on the s-process nucleosynthesis will be discussed. In the second half of this seminar, I will present our experiments to determine neutron capture cross sections of radioactive nuclei using the Surrogate Reaction method [1]. Neutron capture reactions for the s-process involve relatively long-lived nuclei neighboring stability in the nuclear chart. Therefore, the Surrogate Reaction, which creates the same compound nuclei as the neutron capture reaction using a stable beam and target, can be a useful approach. On the other hand, the r- process, which produces the other half

5

  1. Special Particle Phyics Seminar

    10:30 am, Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

6

  1. RIKEN/NT & Quantum Computing Seminar

    12:30 pm, Building 510, Room 2-160

    Hosted by: Rob Pisarski

    I will discuss the uncertainty in quantum mechanics as a property reflecting the "quantity" (measure) on the set of possible probing outcomes. This is in contrast to the commonly used "spectral distance" (metric). An unexpected insight into the nature of quantum uncertainty (and that of measure) is obtained as a result. One of the motivations for considering measure uncertainty is that it is directly relevant for assessing the efficiency of quantum computation.

7

  1. Condensed-Matter Physics & Materials Science Seminar

    11 am, ISB Bldg. 734 Conference Room 201 (upstairs)

    Hosted by: Ivan Bozovic

    Quantum phase transitions (QPT) between distinct ground states of matter are widespread phenomena, yet there are only a few experimentally accessible systems where the microscopic mechanism of the transition can be tested and understood. In this talk we will report on discovery that a magnetic-field driven quantum phase transition in MoGe superconducting nanowires can be fully explained by the critical theory of pair-breaking transitions characterized by a correlation length exponent v≈1 and dynamic critical exponent z≈ 2. We find that in the quantum critical regime, the electrical conductivity is in agreement with a theoretically predicted scaling function and, moreover, that the theory quantitatively describes the dependence of conductivity on the critical temperature, field magnitude and orientation, nanowire cross-sectional area, and microscopic parameters of the nanowire material. At the critical field, the conductivity follows a T^(d–2)/z dependence predicted by phenomenological scaling theories and more recently obtained within a holographic framework. Our work uncovers the microscopic processes governing the transition: the pair-breaking effect of the magnetic field on interacting Cooper pairs overdamped by their coupling to electronic degrees of freedom. It also reveals the universal character of continuous quantum phase transitions. In the talk we will also briefly comment on reliability of the finite-size scaling analysis, origin of zero-bias anomaly in wires and implication of our finding for QPT in superconducting films.

  2. Nuclear Theory/RBRC Seminar

    2 pm, Small Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    Recently we have outlined the general phase structure of the above relevant theory set, inferred from probing the glue by external Dirac probes. Its novelty and simplicity stems from the conclusion that changes in temperature, mass and number of flavors lead to analogous dynamical effects. In this talk I will review that picture, and introduce an important refinement of it that is currently emerging in the thermal corner of the phase diagram.

8

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9

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10

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11

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12

  1. Joint BNL/RIKEN HET Seminar

    2 pm, Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    Since the discovery of a Higgs boson in 2012 at CERN, accessing its properties is one of the main goals of the Large Hadron Collider (LHC) experimental collaborations. The triple Higgs coupling in particular is a primary target as it would be a direct probe of the shape of the scalar potential at the origin of the electroweak-symmetry-breaking mechanism, and is directly accessed via the production of a pair of Higgs bosons. In this view, it is of utmost importance to reach high precision in the theoretical prediction of Higgs boson pair production cross section at the LHC. I will present in this talk the calculation of the 2-loop QCD corrections to the Higgs-pair-production cross section via gluon fusion, that is the main production mechanism, including the top-quark mass effects in the loops. It will be shown that they can be significant in the Higgs-pair-mass differential distributions.

13

  1. RIKEN Lunch Seminar

    12:30 pm, Building 510, Room 2-160

  2. Particle Physics Seminar

    3 pm, Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    The Higgs boson observation by ATLAS and CMS Collaborations at the CERN Large Hadron Collider has completed the Standard Model; the culmination of a century of discoveries. Despite the overwhelming success of the Standard Model to-date, the origin of fermion masses through Yukawa couplings to the Higgs doublet is loosely constrained experimentally and offers opportunities for BSM physics contributions. The status of the determination of the Higgs boson Yukawa couplings at the LHC will be presented and the prospects for the future will be discussed.

14

  1. HET Lunch Seminar

    12:15 pm, Building 510, Room 2-160

    Hosted by: Mattia Bruno

15

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16

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17

  1. Special Particle Physics Seminar

    1 pm, Small Seminar Room, Bldg. 510

    Hosted by: David Jaffe

    During the 2000s, the BaBar experiment at SLAC (Stanford/USA) and the Belle experiment at KEK (Tsukuba/Japan) performed a very successful flavor physics program. BaBar and Belle discovered CP violation in the B meson system and put tight experimental constraints on the quark-flavor sector of the Standard Model. The excellent experimental confirmation of the theory predictions by BaBar and Belle led to the Nobel Prize in physics for Makoto Kobayashi and Toshihide Maskawa in 2008. Continuing on these efforts, the new high-luminosity accelerator SuperKEKB and the next-generation B factory experiment Belle II recently started operation at KEK in Japan. SuperKEKB is designed to operate at an instantaneous luminosity of 8x10^35/cm^2/s, which is a factor 40 higher than the world record achieved by its predecessor KEKB. The upgraded Belle II detector will collect data samples about two orders of magnitudes larger than those of the BaBar and Belle experiments. In this talk, we introduce to flavor physics and CP violation. We will present recent results of a combined analysis campaign, which for the first time makes simultaneous use of the large final data samples of BaBar and Belle in single physics analyses. The approach provides access to an integrated luminosity of about 1.1 inverse attobarn, and thus allows to perform early Belle II-like measurements. In addition, ongoing work of the speaker at LHCb is reported. At the end of the talk, the prospects for the new physics searches in heavy flavor decays governed by quantum-loop effects at Belle II are briefly discussed.

18

  1. Physics Colloquium

    3:30 pm, Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    Particle colliders have been remarkably successful tools in particle and nuclear physics. What are the future trends and limitations of accelerators as they currently exist, and are there possible alternative approaches? What would the ultimate collider look like? This talk examines some challenges and possible solutions. Accelerating a single particle rather than a thermal distribution may allow exploration of more controlled interactions without background. Also, cost drivers are possibly the most important limiting factor for large accelerators in the foreseeable future so emerging technologies to reduce cost are highlighted.

19

  1. No events scheduled

20

  1. Condensed-Matter Physics & Materials Science Seminar

    1:30 pm, ISB 734 Conference Room 201

    Hosted by: Andreas Weichselbaum

    The functional renormalization group (fRG) is a versatile, quantum-field-theoretical formulation of the powerful RG idea and has seen a large number of successful applications. The main limitation of this framework is the truncation of the hierarchy of flow equations, where typically effective three-particle interactions are neglected altogether. From another perspective, the parquet formalism consists of self-consistent many-body relations on the one- and two-particle level and allows for the most elaborate diagrammatic resummations. Here, we unify these approaches by deriving multiloop fRG flow equations from the self-consistent parquet relations [1]. On the one hand, this circumvents the reliance on higher-point vertices within fRG and equips the method with quantitative predictive power [2]. On the other hand, it enables solutions of the parquet equations in previously unaccessible regimes. Using the X-ray-edge singularity as an example, we introduce the formalism and illustrate our findings with numerical results [3]. Finally, we discuss applications to the 2D Hubbard model [4] and the combination of multiloop fRG with the dynamical mean-field theory. [1] F. B. Kugler and J. von Delft, arXiv:1807.02898 (2018) [2] F. B. Kugler and J. von Delft, PRB 97, 035162 (2018) [3] F. B. Kugler and J. von Delft, PRL 120, 057403 (2018) [4] A. Tagliavini, C. Hille, F. B. Kugler, S. Andergassen, A. Toschi, and C. Honerkamp, arXiv:1807:02697 (2018)

  2. Particle Physics Seminar

    3 pm, Small Seminar Room, Bldg. 510

    Hosted by: David Jaffe

    The first generation of B-Factories, BaBar and Belle, operated over the previous decade and produced many world-leading measurements related to flavor physics. Their discoveries contributed to the awarding of the 2008 Nobel Prize in Physics. The Belle II experiment, now underway at the KEK laboratory in Japan, is a substantial upgrade of both the Belle detector and the KEKB accelerator. It aims to collect 50 times more data than existing B-Factory samples. This will provide unprecedented sensitivity to new physics signatures in the flavor sector. This talk will present the upgrade efforts of the Belle II experiment, results from its recent first e+e- collisions, and the future physics opportunities the experiment will provide.

21

  1. HET Lunch Discussions

    12:15 pm, Building 510, Room 2-160

    Hosted by: Christoph Lehner

  2. Nuclear Theory/RIKEN Seminar

    2 pm, Building 510, CFNS Seminar Room 2-38

    Hosted by: Andrey Tarasov

    Pythia 8 is a general-purpose Monte-Carlo event generator widely used to simulate high-energy proton-proton collisions at the LHC. Recently it has been extended to handle also other collision systems involving lepton and heavy-ion beams. In this seminar I will review the current Pythia 8 capabilities in processes relevant to an Electron-Ion Collider (EIC) and discuss about the projected future improvements. The relevant processes can be divided into two regions based on the virtuality of the intermediate photon: deeply inelastic scattering (DIS) at high virtualities and photoproduction at low virtualities. I will begin with an introduction of the event generation steps in Pythia 8 and then briefly discuss how the DIS processes can be simulated. Then I present our photoproduction framework and compare the results to the HERA data for charged-hadron and dijet production in lepton-proton collisions. In particular I discuss about the role of multiparton interactions in photon-proton interactions with resolved photons and how these can be constrained with the existing HERA data. Then I discuss how the same framework can be applied to ultra-peripheral heavy-ion collisions at the LHC where one can study high-energy photon-nucleus interactions in a kinematic region comparable to EIC. Finally I will show our first predictions for dijet production in these events and quantify the contribution of diffractive events according to the hard diffractionmodel that has been recently implemented into Pythia 8.

22

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23

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24

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25

  1. SEP

    25

    Tuesday

    Particle Physics Seminar

    3 pm, Small Seminar Room, Bldg. 510

    Tuesday, September 25, 2018, 3:00 pm

    Hosted by: Alessandro Tricoli

    The branching ratio of the Standard Model (SM) Higgs boson to non-SM or "exotic" states is currently constrained to be less than 34% at 95% confidence level. This opens possibility to search for new particles in the decays of the Higgs boson. Such searches could provide a unique access to hidden-sector states that are singlets under the SM gauge transformations. A search for decays of the Higgs boson to a pair of new spin–0 particles, H → aa, where the a–bosons decay to a b-quark pair and a muon pair, is presented in this seminar. The analysis uses 36.1 fb−1 of proton-proton collisions data with √s = 13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No deviation from the Standard Model prediction is observed and limits on Br(H → aa → bbμμ) are set in the a–boson mass range of 20–60 GeV. Searches in other final states, such as four b-quarks (H → aa → 4b) and two jets and two photons (H → aa → ggγγ), are also discussed.

  2. SEP

    25

    Tuesday

    Physics Colloquium

    3:30 pm, Large Seminar Room, Bldg. 510

    Tuesday, September 25, 2018, 3:30 pm

    Hosted by: Rob Pisarski

    The US-based Electron-Ion Collider (EIC) is a future high-luminosity, polarized collider dedicated to the physics of the nucleon/nucleus structure. Among the many physics problems that can be addressed at the EIC, I will focus on the origin of the mass and spin of the nucleon, namely, how they can be understood in terms of quarks' and gluons' degrees of freedom. I will give a review of the mass and spin decompositions in QCD and discuss possible experimental observables.

26

  1. SEP

    26

    Wednesday

    HET Seminar

    2 pm, Small Seminar Room, Bldg. 510

    Wednesday, September 26, 2018, 2:00 pm

    Hosted by: Christopher Murphy

27

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28

  1. SEP

    28

    Friday

    Nuclear Theory/RIKEN Seminar

    2 pm, Building 510, CFNS Seminar Room 2-38

    Friday, September 28, 2018, 2:00 pm

    Hosted by: Chun Shen

29

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30

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  1. SEP

    25

    Tuesday

    Particle Physics Seminar

    "Searches for decays of a Higgs boson into pairs of light (pseudo)scalars with the ATLAS detector"

    Presented by Ljiljana Morvaj

    3 pm, Small Seminar Room, Bldg. 510

    Tuesday, September 25, 2018, 3:00 pm

    Hosted by: Alessandro Tricoli

    The branching ratio of the Standard Model (SM) Higgs boson to non-SM or "exotic" states is currently constrained to be less than 34% at 95% confidence level. This opens possibility to search for new particles in the decays of the Higgs boson. Such searches could provide a unique access to hidden-sector states that are singlets under the SM gauge transformations. A search for decays of the Higgs boson to a pair of new spin–0 particles, H → aa, where the a–bosons decay to a b-quark pair and a muon pair, is presented in this seminar. The analysis uses 36.1 fb−1 of proton-proton collisions data with √s = 13 TeV recorded by the ATLAS experiment at the LHC in 2015 and 2016. No deviation from the Standard Model prediction is observed and limits on Br(H → aa → bbμμ) are set in the a–boson mass range of 20–60 GeV. Searches in other final states, such as four b-quarks (H → aa → 4b) and two jets and two photons (H → aa → ggγγ), are also discussed.

  2. SEP

    25

    Tuesday

    Physics Colloquium

    "Unraveling the nucleon's mass and spin structure at an Electron-Ion Collider"

    Presented by Yoshitaka Hatta, BNL and Kyoto University

    3:30 pm, Large Seminar Room, Bldg. 510

    Tuesday, September 25, 2018, 3:30 pm

    Hosted by: Rob Pisarski

    The US-based Electron-Ion Collider (EIC) is a future high-luminosity, polarized collider dedicated to the physics of the nucleon/nucleus structure. Among the many physics problems that can be addressed at the EIC, I will focus on the origin of the mass and spin of the nucleon, namely, how they can be understood in terms of quarks' and gluons' degrees of freedom. I will give a review of the mass and spin decompositions in QCD and discuss possible experimental observables.

  3. SEP

    26

    Wednesday

    HET Seminar

    "Loop-Induced Single Top Partner Production and Decay at the HL-LHC"

    Presented by Jeong Han Kim, Kansas University

    2 pm, Small Seminar Room, Bldg. 510

    Wednesday, September 26, 2018, 2:00 pm

    Hosted by: Christopher Murphy

  4. SEP

    28

    Friday

    Nuclear Theory/RIKEN Seminar

    "TBA"

    Presented by Jordy De Vries, UMass Amherst

    2 pm, Building 510, CFNS Seminar Room 2-38

    Friday, September 28, 2018, 2:00 pm

    Hosted by: Chun Shen

  5. OCT

    1

    Monday

    Particle Physics Seminar

    "Results from NA62 and its future program"

    Presented by Babette Döbrich, CERN

    3 pm, Small Seminar Room, Bldg. 510

    Monday, October 1, 2018, 3:00 pm

    Hosted by: Alessandro Tricoli

    The decay K+→π+νν, with a very precisely predicted branching ratio of less than 10^{-10}, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at CERN SPS is designed to measure the branching ratio of the K+→π+νν with a decay-in-flight technique, novel for this channel. NA62 took data in 2016, 2017 and another year run is scheduled in 2018. Statistics collected in 2016 allows NA62 to reach the Standard Model sensitivity for K+→π+νν, entering the domain of 10-10 single event sensitivity and showing the proof of principle of the experiment. The analysis data is reviewed and the preliminary result from the 2016 data set presented. In addition, owing to the high beam-energy and a hermetic detector coverage, NA62 also has the opportunity to directly search for a plaethora of long-lived beyond-the Standard Model particles, such as Axion-like Particles and Dark Photons. We will review the status and results of this searches and give prospects for future data taking at NA62.

  6. OCT

    2

    Tuesday

    Nuclear Physics Seminar

    "Exporing the Phase Diagram with Succeptibility Scaling Functions: Epic Voyage or Just Another Bad Trip"

    Presented by Roy A Lacey, Stony Brook University

    11 am, Small Seminar Room, Bldg. 510

    Tuesday, October 2, 2018, 11:00 am

    Hosted by: Jiangyong Jia

    A major goal of the ongoing experimental programs at RHIC is to chart the QCD phase diagram.Pinpointing the location of the first order phase boundary which terminates at a critical end point (CEP), in the temperature versus baryon chemical potential (T,µB) plane of this phase diagram, is key to this mapping. Finite-Size-Finite-Time succeptibility scaling functions can give crucial insight on these essential landmarks of the phase diagram. I will discuss recent attempts to extract and use such scaling functions to pin down the location of the CEP, as well as the associated critical exponents required to identify its universality class.

  7. OCT

    4

    Thursday

    Special Particle Physics Seminar

    "Latest XENON1T results"

    Presented by Qing Lin, Columbia University

    1 pm, Small Seminar Room, Bldg. 510

    Thursday, October 4, 2018, 1:00 pm

    Hosted by: Chao Zhang

    Understanding the properties of dark matter particle is a fundamental problem in particle physics and cosmology. The search of dark matter particle scattering off nuclei target using ultra-low background detector is one of the most promising technology to decipher the nature of dark matter. The XENON1T experiment, which is a dual phase detector with ~2.0 tons of xenon running at the Gran Sasso Laboratory in Italy, is designed to lead the field of dark matter direct detection. Since November 2016, the XENON1T detector is continuously taking data, with a background rate of more than one order of magnitude lower than any current generation dark matter search experiment. In this talk, I will present the latest results from XENON1T. Details about the XENON1T detector as well as the data analysis techniques will also be covered.

  8. OCT

    4

    Thursday

    Particle Physics Seminar

    "SB/BNL Joint Cosmo seminar: Weighing Galaxy Clusters with Weak Lensing in Hyper Suprime-Cam Survey"

    Presented by Dr. Elinor Medezinski, Princeton University

    3 pm, Small Seminar Room, Bldg. 510

    Thursday, October 4, 2018, 3:00 pm

    Hosted by: Chi-Ting Chang

    The most fundamental question in observational cosmology today is what is the nature of dark energy and dark matter. Clusters of galaxies serve as beacons to the growth of structure over cosmic scales, making them a sensitive cosmological tool. However, accurately measuring their masses has been notoriously difficult. Weak lensing provides the best direct probe of the cluster mass, both the baryonic and dark components, but it requires high-quality wide-field imaging and careful control of systematics. With its unprecedentedly deep and exquisite seeing, the Subaru Hyper Suprime-Cam (HSC) survey is an ongoing campaign to observe 1,400 square degrees to r~26, providing the closest precursor to LSST. In this talk, I will present our new field-leading results from the first HSC data release of ~150 square degrees that encompass thousands of clusters. Harnessing our new HSC survey, I measure benchmark weak lensing cluster masses with improved methodology, and reconcile previous tension on cosmological parameters between the SZ and CMB within the Planck survey. In the next decade, LSST and WFIRST will discover hundreds of thousands of galaxy clusters, peering deep to the epoch of formation. I will describe these surveys and the multifold breakthrough science we will achieve in the new era of astronomy.

  9. OCT

    10

    Wednesday

    HET/RIKEN Seminar

    "TBA"

    Presented by Shaouly Bar-Shalom, Weizman

    2:30 pm, Small Seminar Room, Bldg. 510

    Wednesday, October 10, 2018, 2:30 pm

  10. OCT

    11

    Thursday

    Particle Physics Seminar

    "Higgs to beauty quarks"

    Presented by Caterina Vernieri, SLAC

    3 pm, Small Seminar Room, Bldg. 510

    Thursday, October 11, 2018, 3:00 pm

    Hosted by: Alessandro Tricoli

    The Higgs boson discovery at the LHC marked a historic milestone in the study of fundamental particles and their interactions. Over the last six years, we have begun measuring its properties, which are essential to build a deep understanding of the Higgs sector of the Standard Model and to potentially uncover new phenomena. The Higgs' favored decay mode to beauty (b) quarks (~60%) had so far remained elusive because of the overwhelming background of b-quark production due to strong interactions. Observing the Higgs decay to b-quarks was one of the critical missing pieces of our knowledge of the Higgs sector. Measuring this decay is a fundamental step to confirm the mass generation for fermions and may also provide hints of physics beyond the Standard Model. The CMS observation of the decay of the SM Higgs boson into a pair of b-quarks exploiting an exclusive production mode (VH) is yet another major milestone. This experimental achievement at the LHC, considered nearly impossible in the past, makes use of several advanced machine learning techniques to identify the b-quark distinctive signature, improve the Higgs boson mass resolution, and discriminate the Higgs boson signal from background processes.

  11. OCT

    11

    Thursday

    NSLS-II Colloquium Series

    "Biophysical Studies of an RNA Virus particle and its Maturation: Insights into an Elegantly Programmed Nano-machine"

    Presented by John E. (Jack) Johnson, Department of Integrative Structural and Computational Biology, The Scripps Research Institute

    4 pm, Large Seminar Room, Bldg. 510

    Thursday, October 11, 2018, 4:00 pm

    Hosted by: John Hill

    Nudaurelia Capensis ? Virus (N?V) is a eukaryotic, quasi-equivalent, RNA virus, with a T=4 surface lattice, where maturation is dramatic (a change in particle size of 100Å) and is novel in that it can be investigated in vitro. Here we use X-ray crystallography, biochemistry, Small Angle X-ray Scattering, and electron cryo-microscopy and image reconstruction (CryoEM), to characterize maturation intermediates, an associated auto-catalytic cleavage, the kinetics of morphological change and to demonstrate that regions of N?V subunit folding are maturation-dependent and occur at rates determined by their quasi-equivalent position in the capsid. Matsui, T., Lander, G. C., Khayat, R., and Johnson, J. E. 2010. Subunits fold at position-dependent rates during maturation of a eukaryotic RNA virus. Proc Natl Acad Sci U S A 107:14111-5. Veesler, D., and Johnson, J.E. 2012. Virus Maturation. Annual review of biophysics 41:473-496. Doerschuk, P. C., Gong, Y., Xu, N., Domitrovic, T., and Johnson, J. E. 2016. Virus particle dynamics derived from CryoEM studies. Curr Opin Virol 18:57-63.

  12. OCT

    12

    Friday

    Nuclear Theory/RBRC Seminar

    "TBA"

    Presented by Srimoyee Sen, University of Arizona

    2 pm, Building 510, Room 2-160

    Friday, October 12, 2018, 2:00 pm

    Hosted by: Andrey Tarasov

  13. OCT

    15

    Monday

    Condensed-Matter Physics & Materials Science Seminar

    "In-situ Investigation of Crystallization of a Metallic Glass by Bragg Coherent X-ray Diffraction"

    Presented by Bo Chen, Tongji University, China

    11 am, ISB Bldg. 734, Conf. Rm. 201 (upstairs)

    Monday, October 15, 2018, 11:00 am

    Hosted by: Ian Robinson

    The crystallization behaviour of metallic glass (MG) has long been investigated ever since the discovery of these important functional materials [1]. Compared with crystalline and amorphous extremes, mate-rials containing crystalline precipitates within an otherwise amorphous MG or partially crystallized ma-terials have distinct properties that could be a way of tuning the materials' characteristics. Several methods including powder X-ray diffraction (XRD), transmission electron microscope (TEM) and se-lected area electron diffraction (SAED) are usually combined to characterize the degree of crystalline structure in amorphous materials. Until now, these methods, however, have failed to show the crystal-lization of individual crystal grains in three dimensions. In this work, the in-situ Bragg coherent X-ray diffraction imaging (BCDI) [2, 3] reveals the grain growth and the strain variation of individual crystals up to the sizes of a few hundred nanometers from the pure Fe-based MG powder during heating. We have found that there is preferential growth along one direction during the crystal formation; there is fractal structure around the developing crystal surface; there is also strain relaxation within the growing crystals while cooling. The work supports a two-step crystallization model for the Fe-based MG during heating. This could help to pave the way for designing partially crystalline materials with their at-tendant soft magnetic, anti-corrosive and mechanical properties. References [1] D. H. Kim, W. T. Kim, E. S. Park, N. Mattern, and J. Eckert, Prog. Mater. Sci. 2013, 58, 1103. [2] M. A. Pfeifer, G. J. Williams, I. A. Vartanyants, R. Harder and I. K. Robinson, Nature 2006, 442, 63. [3] I. K. Robinson and R. Harder, Nat. Mater. 2009, 8, 291.

  14. OCT

    17

    Wednesday

    HET Seminar

    "TBA"

    Presented by Alejandro Vaquero, University of Utah

    2:30 pm, Small Seminar Room, Bldg. 510

    Wednesday, October 17, 2018, 2:30 pm

    Hosted by: Aaron Meyer

  15. OCT

    18

    Thursday

    Particle Physics Seminar

    "ATLAS Di-boson resonance searches"

    Presented by Viviana Cavaliere, Brookhaven National Lab

    3 pm, Small Seminar Room, Bldg. 510

    Thursday, October 18, 2018, 3:00 pm

    Hosted by: Alessandro Tricoli

  16. OCT

    19

    Friday

    Nuclear Theory/RIKEN Seminar

    "TBA"

    Presented by Aleksas Mazeliauskas, University of Heidelberg

    2 pm, Building 510, CFNS Seminar Room 2-38

    Friday, October 19, 2018, 2:00 pm

    Hosted by: Chun Shen

  17. OCT

    30

    Tuesday

    Physics Colloquium

    "Cosmic Chandlery with Thermonuclear Supernovae"

    Presented by Alan Calder, Stony Brook University

    3:30 pm, Large Seminar Room, Bldg. 510

    Tuesday, October 30, 2018, 3:30 pm

    Hosted by: Rob Pisarski

    Thermonuclear (Type Ia) supernovae are bright stellar explosions distinguished by light curves that can be calibrated to allow for their use as "standard candles" for measuring cosmological distances. Our research investigates how properties of the host galaxy such as composition and age influence properties of the progenitor system, which in turn influence the thermonuclear burning during an event and thus its brightness. I will present the results from ensembles of simulations addressing the influence of age and composition on the brightness of an event. These results show that the outcome depends sensitively on the nuclear burning, particularly weak interactions. Thus precise measurement of the largest possible scales of the Universe requires accurately capturing physics at some of the smallest scales.

  18. OCT

    31

    Wednesday

    HET Seminar

    "Probing New Physics at the Radiation-zero Point in W+Z/gamma Production"

    Presented by Rodolfo Capdevilla, Notre Dame

    2:30 pm, Small Seminar Room, Bldg. 510

    Wednesday, October 31, 2018, 2:30 pm

    Hosted by: Gopolang Mohlabeng

  19. OCT

    31

    Wednesday

    HET Seminar

    "Probing New Physics effects at the Radiation Amplitude Zero at the LHC"

    Presented by Rodolfo Capdevilla, Notre Dame

    2:30 pm, Small Seminar Room, Bldg. 510

    Wednesday, October 31, 2018, 2:30 pm

    Hosted by: Gopolang Mohlabeng

  20. NOV

    1

    Thursday

    Particle Physics Seminar

    "Search of the rare decay of KL→π0νν at J-PARC"

    Presented by Yu-Chen, Tung

    3 pm, Small Seminar Room, Bldg. 510

    Thursday, November 1, 2018, 3:00 pm

    Hosted by: Chao Zhang

    J-PARC KOTO is a dedicated experiment to search for the rare KL→π0νν decay. This decay is special not only because of its direct CP violating process, but also its theoretical cleanness. In the standard model, the branching ratio of KL→π0νν is calculated to be 3×10-11 with only a few percent uncertainty, which provides a clean base to explore new physics through finding deviations from the standard model. In the recently released results of data collected in 2015, the sensitivity of search was improved by an order of magnitude from the previous result and no event was observed in the signal region, with the prediction of 0.4 background event. In this talk, I will report the analysis and DAQ plan toward the sensitivity of O(-11).

  21. NOV

    2

    Friday

    Nuclear Theory/RBRC Seminar

    "TBA"

    Presented by Al Mueller, Columbia University

    2 pm, Building 510, Room 2-38

    Friday, November 2, 2018, 2:00 pm

    Hosted by: Andrey Tarasov

  22. NOV

    7

    Wednesday

    Joint YITP/HET Theory Seminar

    "TBA"

    Presented by TBA

    2:30 pm, Small Seminar Room, Bldg. 510

    Wednesday, November 7, 2018, 2:30 pm

  23. NOV

    8

    Thursday

    Condensed-Matter Physics & Materials Science Seminar

    "Phase transitions, emergent symmetries and quantum critical behavior of Dirac systems"

    Presented by Michael Scherer, University of Cologne, Germany

    1:30 pm, ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Thursday, November 8, 2018, 1:30 pm

    Hosted by: Laura Classen

    TBA

  24. NOV

    14

    Wednesday

    HET Seminar

    "TBA"

    Presented by Konstantinos Orginos, College of William and Mary

    2:30 pm, Small Seminar Room, Bldg. 510

    Wednesday, November 14, 2018, 2:30 pm

    Hosted by: Aaron Meyer

  25. NOV

    29

    Thursday

    Particle Physics Seminar

    "The structure of the proton in the LHC precision era"

    Presented by Juan Rojo, Vrije Universiteit Amsterdam and Nikhef

    3 pm, Small Seminar Room, Bldg. 510

    Thursday, November 29, 2018, 3:00 pm

    Hosted by: Alessandro Tricoli

    The determination of the partonic structure of the proton is a central component of the precision phenomenology program at the Large Hadron Collider (LHC). This internal structure of nucleons is quantified in the collinear QCD factorization framework by the Parton Distribution Functions (PDFs), which encode the probability of finding quarks and gluons inside the proton carrying a given amount of its momentum. PDFs cannot currently be computed from first principles, and therefore they need to be determined from experimental data from a variety of hard-scattering cross-sections in lepton-proton and proton-proton collisions. This program, known as the global QCD analysis, involves combining the most PDF-sensitive data and the highest precision QCD and electroweak calculations available within a statistically robust fitting methodology. In this talk I review our current understanding of the quark and gluon structure of the proton, which emphasis for the implications for precision LHC phenomenology and searches for new physics, but also exploring other aspects of the nucleon structure such as their impact on high-energy neutrino telescopes, the connection with lattice QCD calculations, and the onset of novel small-x dynamics beyond the collinear framework. Finally, I highlight the prospects for improving our understanding of the quark/gluon structure of the nucleon at the high-luminosity LHC era.

  26. NOV

    30

    Friday

    Nuclear Theory/RBRC Seminar

    "TBA"

    Presented by Juan Rojo, VU University

    2 pm, Building 510, Room 2-38

    Friday, November 30, 2018, 2:00 pm

    Hosted by: Andrey Tarasov

  27. DEC

    6

    Thursday

    Particle Physics Seminar

    "W mass and Weinberg angle measurments at ATLAS"

    Presented by Matthias Schott

    3 pm, Small Seminar Room, Bldg. 510

    Thursday, December 6, 2018, 3:00 pm

    Hosted by: Alessandro Tricoli

  28. JAN

    10

    Thursday

    Particle Physics Seminar

    "Cross section measurements and new physics searches with WZ vector boson scattering events at CMS"

    Presented by Kenneth Long, University of Wisconsin - Madison

    3 pm, Small Seminar Room, Bldg. 510

    Thursday, January 10, 2019, 3:00 pm

    Hosted by: Alessandro Tricolli

    As the standard model (SM) Higgs boson looks increasingly like its SM expectation, expanded tests of the electroweak (EW) sector of the SM are a focal point of the long-term LHC program. Production of massive vector bosons via vector boson scattering provides a direct probe of the self-interactions of the massive vector bosons, which are intimately connected to the Higgs-Englert-Brout mechanism of EW symmetry breaking. A search for vector boson scattering of W and Z bosons has recently been performed by the CMS experiment using data collected in 2016. I will present this search as well as WZ cross section measurements, which are less dependent on theoretical inputs. This process is also sensitive to New Physics in the EW sector. I will present interpretations of these results in terms of explicit models predicting additional charged Higgs bosons and in the generalized framework of dimension-8 effective field theory.

  1. Nuclear Theory/RIKEN Seminar

    "Status of Pythia 8 for an Electron-Ion Collider"

    Presented by Ilkka Helenius, University of Tubingen

    Friday, September 21, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Andrey Tarasov

    Pythia 8 is a general-purpose Monte-Carlo event generator widely used to simulate high-energy proton-proton collisions at the LHC. Recently it has been extended to handle also other collision systems involving lepton and heavy-ion beams. In this seminar I will review the current Pythia 8 capabilities in processes relevant to an Electron-Ion Collider (EIC) and discuss about the projected future improvements. The relevant processes can be divided into two regions based on the virtuality of the intermediate photon: deeply inelastic scattering (DIS) at high virtualities and photoproduction at low virtualities. I will begin with an introduction of the event generation steps in Pythia 8 and then briefly discuss how the DIS processes can be simulated. Then I present our photoproduction framework and compare the results to the HERA data for charged-hadron and dijet production in lepton-proton collisions. In particular I discuss about the role of multiparton interactions in photon-proton interactions with resolved photons and how these can be constrained with the existing HERA data. Then I discuss how the same framework can be applied to ultra-peripheral heavy-ion collisions at the LHC where one can study high-energy photon-nucleus interactions in a kinematic region comparable to EIC. Finally I will show our first predictions for dijet production in these events and quantify the contribution of diffractive events according to the hard diffractionmodel that has been recently implemented into Pythia 8.

  2. HET Lunch Discussions

    "GeV-Scale Messengers of Planck-Scale Dark Matter"

    Presented by Gopolang Mohlabeng, BNL

    Friday, September 21, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  3. Particle Physics Seminar

    "The Belle II Experiment"

    Presented by Bryan Fulsom, PNNL

    Thursday, September 20, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: David Jaffe

    The first generation of B-Factories, BaBar and Belle, operated over the previous decade and produced many world-leading measurements related to flavor physics. Their discoveries contributed to the awarding of the 2008 Nobel Prize in Physics. The Belle II experiment, now underway at the KEK laboratory in Japan, is a substantial upgrade of both the Belle detector and the KEKB accelerator. It aims to collect 50 times more data than existing B-Factory samples. This will provide unprecedented sensitivity to new physics signatures in the flavor sector. This talk will present the upgrade efforts of the Belle II experiment, results from its recent first e+e- collisions, and the future physics opportunities the experiment will provide.

  4. Condensed-Matter Physics & Materials Science Seminar

    "Multiloop functional renormalization group: Exact flow equations from the self-consistent parquet relations"

    Presented by Fabian Kugler, Ludwig-Maximilians-Universitat Munchen, Germany

    Thursday, September 20, 2018, 1:30 pm
    ISB 734 Conference Room 201

    Hosted by: Andreas Weichselbaum

    The functional renormalization group (fRG) is a versatile, quantum-field-theoretical formulation of the powerful RG idea and has seen a large number of successful applications. The main limitation of this framework is the truncation of the hierarchy of flow equations, where typically effective three-particle interactions are neglected altogether. From another perspective, the parquet formalism consists of self-consistent many-body relations on the one- and two-particle level and allows for the most elaborate diagrammatic resummations. Here, we unify these approaches by deriving multiloop fRG flow equations from the self-consistent parquet relations [1]. On the one hand, this circumvents the reliance on higher-point vertices within fRG and equips the method with quantitative predictive power [2]. On the other hand, it enables solutions of the parquet equations in previously unaccessible regimes. Using the X-ray-edge singularity as an example, we introduce the formalism and illustrate our findings with numerical results [3]. Finally, we discuss applications to the 2D Hubbard model [4] and the combination of multiloop fRG with the dynamical mean-field theory. [1] F. B. Kugler and J. von Delft, arXiv:1807.02898 (2018) [2] F. B. Kugler and J. von Delft, PRB 97, 035162 (2018) [3] F. B. Kugler and J. von Delft, PRL 120, 057403 (2018) [4] A. Tagliavini, C. Hille, F. B. Kugler, S. Andergassen, A. Toschi, and C. Honerkamp, arXiv:1807:02697 (2018)

  5. Physics Colloquium

    "Potential and Issues for Future Accelerators and Ultimate"

    Presented by Stephen Brooks, BNL

    Tuesday, September 18, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    Particle colliders have been remarkably successful tools in particle and nuclear physics. What are the future trends and limitations of accelerators as they currently exist, and are there possible alternative approaches? What would the ultimate collider look like? This talk examines some challenges and possible solutions. Accelerating a single particle rather than a thermal distribution may allow exploration of more controlled interactions without background. Also, cost drivers are possibly the most important limiting factor for large accelerators in the foreseeable future so emerging technologies to reduce cost are highlighted.

  6. Special Particle Physics Seminar

    "Flavor physics and CP violation - Recent results from combined BaBar+Belle measurements, ongoing work at LHCb, and prospects for the new physics searches at Belle II"

    Presented by Markus Roehrken, CERN

    Monday, September 17, 2018, 1 pm
    Small Seminar Room, Bldg. 510

    Hosted by: David Jaffe

    During the 2000s, the BaBar experiment at SLAC (Stanford/USA) and the Belle experiment at KEK (Tsukuba/Japan) performed a very successful flavor physics program. BaBar and Belle discovered CP violation in the B meson system and put tight experimental constraints on the quark-flavor sector of the Standard Model. The excellent experimental confirmation of the theory predictions by BaBar and Belle led to the Nobel Prize in physics for Makoto Kobayashi and Toshihide Maskawa in 2008. Continuing on these efforts, the new high-luminosity accelerator SuperKEKB and the next-generation B factory experiment Belle II recently started operation at KEK in Japan. SuperKEKB is designed to operate at an instantaneous luminosity of 8x10^35/cm^2/s, which is a factor 40 higher than the world record achieved by its predecessor KEKB. The upgraded Belle II detector will collect data samples about two orders of magnitudes larger than those of the BaBar and Belle experiments. In this talk, we introduce to flavor physics and CP violation. We will present recent results of a combined analysis campaign, which for the first time makes simultaneous use of the large final data samples of BaBar and Belle in single physics analyses. The approach provides access to an integrated luminosity of about 1.1 inverse attobarn, and thus allows to perform early Belle II-like measurements. In addition, ongoing work of the speaker at LHCb is reported. At the end of the talk, the prospects for the new physics searches in heavy flavor decays governed by quantum-loop effects at Belle II are briefly discussed.

  7. HET Lunch Seminar

    "Isospin-breaking corrections to decay amplitudes in lattice QCD"

    Presented by Davide Giusti, Roma 3, INFN

    Friday, September 14, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Mattia Bruno

  8. Particle Physics Seminar

    "Probing the Higgs Yukawa couplings at the LHC"

    Presented by Konstantinos Nikolopoulos

    Thursday, September 13, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    The Higgs boson observation by ATLAS and CMS Collaborations at the CERN Large Hadron Collider has completed the Standard Model; the culmination of a century of discoveries. Despite the overwhelming success of the Standard Model to-date, the origin of fermion masses through Yukawa couplings to the Higgs doublet is loosely constrained experimentally and offers opportunities for BSM physics contributions. The status of the determination of the Higgs boson Yukawa couplings at the LHC will be presented and the prospects for the future will be discussed.

  9. RIKEN Lunch Seminar

    "Giant photocurrent in asymmetric Weyl semimetals from the helical magnetic effect"

    Presented by Yuta Kikuchi, RBRC

    Thursday, September 13, 2018, 12:30 pm
    Building 510, Room 2-160

  10. Joint BNL/RIKEN HET Seminar

    "Higgs pair production via gluon fusion at NLO QCD"

    Presented by Julien Baglio, Tuebingen U.

    Wednesday, September 12, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    Since the discovery of a Higgs boson in 2012 at CERN, accessing its properties is one of the main goals of the Large Hadron Collider (LHC) experimental collaborations. The triple Higgs coupling in particular is a primary target as it would be a direct probe of the shape of the scalar potential at the origin of the electroweak-symmetry-breaking mechanism, and is directly accessed via the production of a pair of Higgs bosons. In this view, it is of utmost importance to reach high precision in the theoretical prediction of Higgs boson pair production cross section at the LHC. I will present in this talk the calculation of the 2-loop QCD corrections to the Higgs-pair-production cross section via gluon fusion, that is the main production mechanism, including the top-quark mass effects in the loops. It will be shown that they can be significant in the Higgs-pair-mass differential distributions.

  11. Nuclear Theory/RBRC Seminar

    "Temperature, Mass, Flavor: Emerging Phase Structure of SU(3) Gauge Theories with Fundamental Quarks"

    Presented by Ivan Horvath, University of Kentucky

    Friday, September 7, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    Recently we have outlined the general phase structure of the above relevant theory set, inferred from probing the glue by external Dirac probes. Its novelty and simplicity stems from the conclusion that changes in temperature, mass and number of flavors lead to analogous dynamical effects. In this talk I will review that picture, and introduce an important refinement of it that is currently emerging in the thermal corner of the phase diagram.

  12. Condensed-Matter Physics & Materials Science Seminar

    "Pair-breaking quantum phase transition in superconducting nanowires"

    Presented by Andrey Rogachev, University of Utah

    Friday, September 7, 2018, 11 am
    ISB Bldg. 734 Conference Room 201 (upstairs)

    Hosted by: Ivan Bozovic

    Quantum phase transitions (QPT) between distinct ground states of matter are widespread phenomena, yet there are only a few experimentally accessible systems where the microscopic mechanism of the transition can be tested and understood. In this talk we will report on discovery that a magnetic-field driven quantum phase transition in MoGe superconducting nanowires can be fully explained by the critical theory of pair-breaking transitions characterized by a correlation length exponent v≈1 and dynamic critical exponent z≈ 2. We find that in the quantum critical regime, the electrical conductivity is in agreement with a theoretically predicted scaling function and, moreover, that the theory quantitatively describes the dependence of conductivity on the critical temperature, field magnitude and orientation, nanowire cross-sectional area, and microscopic parameters of the nanowire material. At the critical field, the conductivity follows a T^(d–2)/z dependence predicted by phenomenological scaling theories and more recently obtained within a holographic framework. Our work uncovers the microscopic processes governing the transition: the pair-breaking effect of the magnetic field on interacting Cooper pairs overdamped by their coupling to electronic degrees of freedom. It also reveals the universal character of continuous quantum phase transitions. In the talk we will also briefly comment on reliability of the finite-size scaling analysis, origin of zero-bias anomaly in wires and implication of our finding for QPT in superconducting films.

  13. RIKEN/NT & Quantum Computing Seminar

    "Quantum Uncertainty and Quantum Computation"

    Presented by Ivan Horvath, University of Kentucky

    Thursday, September 6, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Rob Pisarski

    I will discuss the uncertainty in quantum mechanics as a property reflecting the "quantity" (measure) on the set of possible probing outcomes. This is in contrast to the commonly used "spectral distance" (metric). An unexpected insight into the nature of quantum uncertainty (and that of measure) is obtained as a result. One of the motivations for considering measure uncertainty is that it is directly relevant for assessing the efficiency of quantum computation.

  14. Special Particle Phyics Seminar

    "LHCb"

    Presented by Angelo Di Canto, CERN

    Wednesday, September 5, 2018, 10:30 am
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

  15. Nuclear Physics Seminar

    "Neutron production and capture in stellar nucleosynthesis:^{22}Ne(\Alpha,n)^{25}Mg reaction and radiative neutron captures of radioactive nuclei"

    Presented by Shuya Ota, Texas A&M University

    Tuesday, September 4, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Jin Huang

    Most of elements heavier than Fe in the Universe are produced by a series of neutron capture reaction and ??-decay in stars. The s-process, which occurs under moderate neutron environments (~107-10 neutrons/cm3) such as in He burning of massive stars, is responsible for producing almost half of the heavy elements. Neutrons for the s-process environment is believed to be supplied by two dominant reactions, one of which is 22Ne(?,n)25Mg reaction. This reaction in massive stars is dominated by a few resonance reactions. Nevertheless, there remain large uncertainties about contribution of the reaction to the s-process nucleosynthesis because the reaction cross sections are too small for direct measurements due to Coulomb barrier (E? = 400-900 keV in the lab system). In the first half of this seminar, I will present our experiment to determine these resonance strengths with a cyclotron accelerator at Texas A&M University. The experiment was performed by an indirect approach using 6Li(22Ne,25Mg+n)d ?-transfer reaction, in which resonance properties such as neutron decay branching ratios of produced 26Mg were studied by measuring deuterons, ?-ray, and 26Mg in coincidence using large arrays of Si and Ge, and a magnetic spectrometer. Our results showed neutron production from 22Ne(?,n)25Mg reaction can be about 10 times lower than past measurements. The effect of our measurements on the s-process nucleosynthesis will be discussed. In the second half of this seminar, I will present our experiments to determine neutron capture cross sections of radioactive nuclei using the Surrogate Reaction method [1]. Neutron capture reactions for the s-process involve relatively long-lived nuclei neighboring stability in the nuclear chart. Therefore, the Surrogate Reaction, which creates the same compound nuclei as the neutron capture reaction using a stable beam and target, can be a useful approach. On the other hand, the r- process, which produces the other half

  16. HET Lunch Discussions

    "Lattice QCD and precision physics from long to short distances: an overview of my 3 years at BNL"

    Presented by Mattia Bruno, BNL

    Friday, August 31, 2018, 12:15 pm
    Building 510, Room 2-95

    Hosted by: Christoph Lehner

  17. Special Nuclear Theory/RIKEN Lunch Seminar

    "Signal-to-noise issues in non-relativistic quantum matter: from entanglement to thermodynamics"

    Presented by Joaquin Drut, University of North Carolina

    Thursday, August 30, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Rob Pisarski

    Non-relativistic quantum matter, as realized in ultracold atomic gases, continues to be a remarkably versatile playground for many-body physics. Experimentalists have exquisite control over temperature, density, coupling, and shape of the trapping potential. Additionally, a wide range of properties can be measured: from simple ones like equations of state to more involved ones like the bulk viscosity and entanglement. The latter has received much attention due to its connection to quantum phase transitions, but it has proven extremely difficult to compute: stochastic methods display exponential signal-to-noise issues of a very similar nature as those due to the infamous sign problem affecting finite-density QCD. In this talk, I will present an algorithm that solves the signal-to-noise issue for entanglement, and I will show results for strongly interacting systems in three spatial dimensions that are the first of their kind. I will also present a few recent explorations of the thermodynamics of polarized matter and other cases that usually have a sign problem, using complexified stochastic quantization.

  18. Nuclear Physics Seminar

    "Probe strong magnetic field in QGP with dielectrons from photon-photon interactions"

    Presented by Zhangbu Xu, BNL

    Tuesday, August 28, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Rongrong Ma

    We presents first measurements of $e^+e^-$ pair production from light-light scattering in non-central heavy ion collisions. The excess yields peak distinctly at low transverse momentum with sqrt() between 40 to 60 MeV/c. The excess yields can be explained only when the photon-photon interactions are included in model calculations. However, the measured pT^2 distributions are significantly broader than model calculation and are different between Au+Au and U+U. Our measurements provide a possible experimental evidence of the existence of strong electromagnetic field. And I will discuss its possible impact on emerging phenomena in hadronic heavy-ion collisions, such as Chiral Magnetic Effect.

  19. Condensed-Matter Physics & Materials Science Seminar

    "Spinon Confinement and a Longitudinal Mode in One Dimensional Yb2Pt2Pb"

    Presented by Bill Gannon, Department of Physics and Astronomy, Texas A&M University

    Thursday, August 23, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Alexei Tsvelik

    Abstract: The Yb3+ magnetic moments in Yb2Pt2Pb are seemingly classical, since the large spin-orbit coupling of the 4f-electrons and the crystal electric field dictate a J = +/-7/2 Yb ground state doublet. Surprisingly, the fundamental low energy magnetic excitations in Yb2Pt2Pb are spinons on one dimensional chains, shown to be in good agreement with the behavior expected with the XXZ Hamiltonian for nearly isotropic, S = +/-1/2 magnetic moments. We have performed new high resolution neutron scattering measurements to examine the properties of these excitations in a magnetic field. In fields larger than 0.5 T, the chemical potential closes the gap to the spinon dispersion, modifying the quantum continuum through the formation of a spinon Fermi surface. This leads to the formation of spinon bound states along the chains, coupled to a longitudinally polarized interchain mode at energies below the quantum continuum. The ground state doublet nature of the Yb ions ensures that at all fields, transverse excitations are virtually nonexistent, allowing direct measurement of the mode dispersion.

  20. RIKEN Lunch Seminar

    "Non-abelian symmetries and applications in tensor networks"

    Presented by Andreas Weichselbaum, BNL

    Thursday, August 23, 2018, 12:30 pm
    Building 510, Room 2-160

  21. Special HET Seminar

    "The Higgs Potential: A Path Toward Discovery"

    Presented by Pier Paolo Giardino, BNL

    Tuesday, August 21, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  22. Nuclear Theory/RBRC Seminar

    "Computation of the shear viscosity in QCD at (almost) next to leading order"

    Presented by Derek Teaney, Stony Brook University

    Friday, August 17, 2018, 2 pm
    Building 510, Room 2-38

  23. HET Lunch Discussions

    "Lattice QCD Study of Exclusive Channels in the Muon HVP"

    Presented by Aaron Meyer, BNL

    Friday, August 17, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

    The hadronic vacuum polarization is a dominant contribution to the theoretical uncertainty of the muon anomalous magnetic moment. Both the R-ratio and Lattice QCD may be used to compute the HVP contribution from theory, and the theoretical uncertainties for both methods are statistically precise in regions that are complimentary to each other. For lattice QCD, the long-distance region dominates the statistical uncertainty. By explicitly studying exclusive channels of the HVP diagram with lattice QCD, it is possible to reconstruct the long-distance behavior of the correlation function. This has the effect of replacing the statistical uncertainty with a significantly smaller systematic uncertainty. With this long-distance reconstruction, it will be possible to achieve a precision with a lattice-only calculation similar to that of the R-ratio method.

  24. RIKEN Lunch Seminar

    "Universality in Classical and Quantum Chaos"

    Presented by Masanori Hanada, YITP

    Thursday, August 16, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    We study the chaotic nature of classical and quantum systems. In particular, we will study the detail of the Lyapunov growth. We will show the evidence that the spectrum of Lyapunov exponents admits universal description by Random Matrix Theory, and systems dual to black holes exhibit 'strong' universality.

  25. Physics Colloquium

    "Quantum computing for deuteron"

    Presented by Thomas Papenbrock, University of Tennessee

    Tuesday, August 14, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

  26. Special HET Seminar

    "New Dark Matter Signals in Neutrino Detectors"

    Presented by Yue Zhang, Northwestern

    Tuesday, August 14, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

  27. Special HET Seminar

    "New Dark Matter Signals in Neutrino Detectors"

    Presented by Yue Zhang, Northwestern

    Monday, August 13, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

  28. Nuclear Theory/RBRC Seminar

    "Electric conductivity of hot and dense quark matter in a magnetic field"

    Presented by Yoshimasa Hidaka, RIKEN

    Friday, August 10, 2018, 2 pm
    Building 510, Room 2-38

    Hosted by: Rob Pisarski

  29. Condensed-Matter Physics & Materials Science Seminar

    "Advances in high energy electron holography"

    Presented by Dr. Toshiaki Tanigaki, Hitachi, Japan

    Friday, August 10, 2018, 1:30 pm
    Conference room in building 480

    Hosted by: MG Han

    Advances in High-Voltage Electron Holography T. Tanigaki Research & Development Group, Hitachi, Ltd. Email: toshiaki.tanigaki.mv@hitachi.com Electron holography can observe electromagnetic field inside materials and devices at high-resolution around atomic scale. The high penetration power of a high energy electron wave is crucial to observing magnetic structures, which exist only in thick samples. It is particularly crucial in three-dimensional (3D) observations, which require a series of sample observations with the sample increasingly tilted so that the projected sample thickness increases with the tilt angle. As an example of this, magnetic vortex cores confined in stacked ferromagnetic (Fe) discs were observed three-dimensionally by using vector-field electron tomography with a 1.0 MV holography electron microscope [1]. To invent new functional materials and devices for establishing a sustainable society, methods for controlling atomic arrangements in small areas such as interfaces have become important [2,3]. Electron holography is a powerful tool for analyzing the origins of functions by observing electromagnetic fields and strains at high resolutions. The advantages of high-voltage electron holography are high resolution and penetration power due to high energy electron waves. The quest for finding the ultimate resolution through continuous improvements on holography electron microscopes led to the development of an aberration corrected 1.2 MV holography electron microscope [4,5] (Figure 1). We describe recent results obtained by using the high-voltage electron holography. Spatial resolution of 1.2 MV holography electron microscope reached 0.043 nm at high-resolutions, when the sample was placed in a high magnetic field of the objective lens [4]. Under the observation conditions, in which the sample was placed in a field-free position for observing a magnetic field, the spatial res

  30. Special HET Seminar

    "Searching for physics beyond the Standard Model at the Intensity Frontier"

    Presented by Martin Hoferichter, University of Washington

    Thursday, August 9, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  31. Special Particle Physics Seminar

    "Deep Neural Network Techniques R&D for Data Reconstruction of Liquid Argon TPC Detectors"

    Presented by Kazuhiro Terao, SLAC National Accelerator Laboratory

    Tuesday, August 7, 2018, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    Liquid Argon Time Projection Chambers (LArTPCs) are capable of recording images of charged particle tracks with breathtaking resolution. Such detailed information will allow LArTPCs to perform accurate particle identification and calorimetry, making it the detector of choice for many current and future neutrino experiments. However, analyzing such images can be challenging, requiring the development of many algorithms to identify and assemble features of the events in order to reconstruct neutrino interactions. In the recent years, we have been investigating a new approach using deep neural networks (DNNs), a modern solution to a pattern recognition for image-like data in the field of Computer Vision. A modern DNN can be applied for various types of problems such as data reconstruction tasks including interaction vertex finding, pixel clustering, and particle/topology type identification. We have developed a small inter-experiment collaboration to share generic software tools and algorithms development effort that can be applied to non-LArTPC imaging detectors. In this talk I will discuss the challenges of LArTPC data reconstruction, recent work and future plans for developing a full LArTPC data reconstruction chain using DNNs.

  32. Special HET Seminar

    "A New Frontier in the Search for Dark Matter"

    Presented by Gordan Krnjaic, FNAL

    Monday, August 6, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    The gravitational evidence for the existence of dark matter is overwhelming; observations of galactic rotation curves, the CMB power spectrum, and light element abundances independently suggest that over 80% of all matter is "dark" and beyond the scope of the Standard Model. However, its particle nature is currently unknown, so discovering its potential non-gravitational interactions is a major priority in fundamental physics. In this talk, I will survey the landscape of light dark matter theories and and introduce an emerging field of fixed-target experiments that are poised to cover hitherto unexplored dark matter candidates with MeV-GeV masses. These new techniques involve direct dark matter production with proton, electron, and *muon* beams at various facilities including Fermilab, CERN, SLAC, and JLab. Exploring this mass range is essential for fully testing a broad, predictive class of theories in which dark matter abundance arises from dark-visible interactions in thermal equilibrium in the early universe.

  33. Summer Sundays

    "Atom Smashing Fun with the Relativistic Heavy Ion Collider"

    Sunday, August 5, 2018, 10 am
    Berkner Hall, Room B

  34. Special HET Seminar

    "New Neutrino Interactions: Breaking Degeneracies and Relaxing Sterile Tensions"

    Presented by Peter Denton, Niels Bohr

    Friday, August 3, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  35. Particle Physics Seminar

    "Significant Excess of Electron-Like Events in the MiniBooNE Short-Baseline Neutrino Experiment"

    Presented by William Louis, Los Alamos National Lab

    Thursday, August 2, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    The MiniBooNE experiment at Fermilab observes a total electron-neutrino event excess in both neutrino and antineutrino running modes of 460.5 +- 95.8 events (4.8 sigma) in the energy range from 200-1250 MeV. The MiniBooNE L/E distribution and the allowed region from a two-neutrino oscillation fit to the data are consistent with the L/E distribution and allowed region reported by the LSND experiment. All of the major backgrounds are constrained by in-situ event measurements, so non-oscillation explanations would need to invoke new anomalous background processes. Although the data are fit with a two-neutrino oscillation model, other models may provide better fits to the data. The MiniBooNE event excess will be further studied by the Fermilab short-baseline neutrino (SBN) program.

  36. RIKEN Lunch Seminar

    "Nucleon isovector axial charge in 2+1-flavor domain-wall QCD with physical mass"

    Presented by Shigemi Ohta, IPNS, KEK

    Thursday, August 2, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

  37. Condensed-Matter Physics & Materials Science Seminar

    "Imaging Non-equilibrium Dynamics in Two-Dimensional Materials"

    Presented by Kenneth Beyerlein, Max Planck Institute for the Structure and Dynamics of Matter, Germany

    Wednesday, August 1, 2018, 11 am
    ISB Bldg. 734, Conf. Rm. 201 (upstairs)

    Hosted by: Ian Robinson

    The interfaces in thin film heterostructures dictate the performance of an electronic device. Understanding their behavior upon exposure to light is important for advancing photovoltaics and spintronics. However, producing an atomic image of these dynamics is an under-determined problem without a unique solution. In this talk, I will show how a set of ultrafast soft X-ray diffraction rocking curves can be spliced together to add constraints to the phase retrieval problem. In doing so, the anti-ferromagnetic order through a NdNiO3 film after illumination of the substrate with a mid-Infrared laser pulse will be imaged. Notably, a disordered phase front initiated at the substrate interface is shown to evolve at twice the speed of sound. This time-spliced imaging technique opens a new window into the correlated dynamics of two-dimensional materials.

  38. Special Particle Physics Seminar

    "Dark Matter Annual Modulation with SABRE"

    Presented by Lindsey Bignell, Australian National University

    Tuesday, July 31, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: David Jaffe

    SABRE is a dark matter direct detection experiment with a target of ultra-pure NaI(Tl). Our experiment is motivated by the DAMA result; a long-standing and highly statistically significant modulation of the count rate in their NaI(Tl) detector that is consistent with that expected from the dark matter halo. However, a number of other direct detection experiments, using different target materials, exclude the dark matter parameter space implied by DAMA for the simplest WIMP-nucleus interaction models. SABRE hopes to carry out the first model-independent test of the DAMA claim, with sufficient sensitivity to confirm or refute their result. SABRE will also operate identical detectors in the northern and southern hemisphere, to rule out seasonally-modulated backgrounds. The southern detector will be housed at the first deep underground laboratory in the Southern Hemisphere: the Stawell Underground Physics Laboratory. This talk will give an overview of the SABRE design and its predicted sensitivity, as well as an update on the proof-of-principle detector which will be operating this summer.

  39. Sambamurti Lecture

    "Capturing the Inner Beauty of the Quark Gluon Plasma"

    Presented by Jin Huang, Brookhaven National Laboratory

    Friday, July 27, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: John Haggerty

    The Quark Gluon Plasma (QGP) filled the universe in the first microsecond after the Big Bang and today is routinely recreated in high energy nuclear collisions at RHIC and the LHC. While experiments have revealed an array of surprising QGP properties, such as perfect fluidity, extreme vorticity, and near total opaqueness to hard scattered quarks and gluons, the detailed physics that gives rise to these properties remains a focus of forefront research. Heavy quarks, particularly the very heavy beauty quark, provide the means to clarify the connection between the microscopic physics of the QGP and its larger scale properties. Beauty quarks – or b-quarks – are produced rarely in collisions at RHIC, and the planned sPHENIX experiment will be equipped with a high rate vertex tracker enabling precision measurements of b-quark observables, such as B-meson suppression and flow, the differential suppression of Upsilon states and a number of observables related to b-quark jets. These b-quark probes will provide crucial information about the microscopic description of QGP at RHIC energies. In this talk, I will explain b-quark physics in the QGP, current measurements, the program at the planned sPHENIX experiment and its relevance to the future Electron Ion Collider.

  40. Nuclear Theory/RIKEN Seminar

    "Jets as a probe of transverse spin physics"

    Presented by Zhongbo Kang, UCLA

    Friday, July 27, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    Jets are collimated spray of hadrons that are naturally produced in high energy colliders. They are powerful probes of many different aspects of QCD dynamics. In this talk, we will demonstrate how to use jets to explore the transverse momentum dependent (TMD) physics. A novel TMD framework to deal with back-to-back two particle correlations is presented, with which we could study the Sivers asymmetry for photon+jet or dijet production in transversely polarized proton-proton collisions. At the end of the talk, we also show how jet substructure could be used to explore the TMD fragmentation functions. We expect these studies to have important applications at RHIC in the future.

  41. Nuclear Theory Seminar

    "Medium Modification of Jet Substructure in the Opacity Expansion"

    Presented by Matthew Sievert, Los Alamos

    Friday, July 27, 2018, 11 am
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Yacine Mehtar-Tani

    The modification of jets and their substructure in the presence of quark-gluon matter, beyond solely the quenching of their production, is a cornerstone of jet tomography. Although the nature of different nuclear environments can vary widely, the manner in which an external potential leads to a modification of jets and their substructure is universal and applies to both hot and cold nuclear matter. An order-by-order calculation of the medium modifications is possible on the basis of the opacity expansion, a series which can be truncated at finite order if the average number of scatterings in the quark-gluon matter is not too large. Other methods exist which can resum the full opacity series into a path integral formalism that remains applicable at very high opacities. In this talk, I will present a new calculation in the opacity expansion approach which computes the gluon substructure of a quark jet with exact kinematics at second order in opacity. I will also derive a set of recursion relations which can be used to construct higher orders terms in the opacity expansion to any finite order. And finally, I will compare this approach to the resumed path integral formalism, discussing the strengths and weaknesses of both methods and opportunities to study their overlap.

  42. Condensed-Matter Physics & Materials Science Seminar

    "Atomic level structural characterization of materials by electron microscopy"

    Presented by Shize Yang, Center for Functional Nanomaterials

    Thursday, July 26, 2018, 4 pm
    Bldg. 480, Conference Room

    Hosted by: Yimei Zhu

    In recent years, with the development of technologies, electron microscopy techniques have been widely developed. Important advancement has been achieved on in-situ electron microscopy, cryogenic electron microscopy, electron tomography, advanced electron energy loss spectroscopy etc. In this talk I will briefly introduce and show how those techniques provide a vital role in the structural characterization of 2D materials, catalysts and battery materials.

  43. Physics Summer School

    "Working with High-Performance Astronomical CCD"

    Presented by Andrei Nomerotski, BNL

    Thursday, July 26, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai and Anze Slosar

  44. Nuclear Theory Seminar

    "Jet fragmentation in a QCD plasma: Universal quark/gluon ratio and wave turbulence"

    Presented by Soeren Schlichting, University of Washington

    Thursday, July 26, 2018, 11 am
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Yacine Mehtar-Tani

    We investigate the radiative break-up of a highly energetic quark or gluon in a high-temperature QCD plasma. Within an inertial range of momenta T

  45. Nuclear Physics Seminar

    "Tale of coherent photon products: from UPC to HHIC"

    Presented by Wangmei Zha, University of Science and Technology of China

    Tuesday, July 24, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Rongrong Ma

  46. Chemistry Department Seminar

    "Triggered Reversible Phase Transformation between Layered and Spinel Structure via Intercalated Hetero Species in Sodium Birnessite"

    Presented by Yong-Mook Kang, Department of Energy and Materials Engineering, Dongguk University-Seoul, Seoul, 04620, Republic of Korea., Korea, Republic of (South)

    Monday, July 23, 2018, 11 am
    Room 300, 3rd Flr. Chemistry Bldg. 555

    Hosted by: Xiao-Qing Yang

    Phase transformation of layered structure into spinel structure has been detrimental for most of layered oxide cathodes. Even if a lot of efforts have been made to relieve this highly irreversible phase transformation, there have been few successful results. However, we firstly observed the possibility to make this irreversible phase transformation extremely reversible by utilizing Na- birnessite (NaxMnO2•yH2O; Na-bir) as a basic structural unit, which has distinctive layered structure containing crystal water. Herein, the crystal water in the structure contributes to generating metastable spinel-like phase, which is the key factor for making this unusual reversibility happen. The reversible structural rearrangement between layered and spinel-like phases during electrochemical reaction could activate new cation sites and enhance ion diffusion with higher structural stability. This unprecedented reversible phase transformation between spinel and layered structure was deeply analyzed via combined ex situ soft and hard X-ray absorption spectroscopy (XAS) analysis with in situ X-ray diffraction (XRD). Fundamental mechanism on this reversible phase transformation was theoretically elucidated and confirmed by kinetic investigation using first-principle calculation. These results provide deep insight into novel class of intercalating materials which can deal with highly reversible framework changes, and thus it can pave an innovative way for the development of cathode materials for next- generation rechargeable batteries.

  47. HET Special Seminar

    "The Quest for Dark Sectors"

    Presented by Claudia Frugiuele, Weizmann

    Friday, July 20, 2018, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    Dark sectors are ubiquitous in physics beyond the Standard Model (SM), and may play a role in explaining many of the long-standing problems of the SM such as the existence of dark matter or the electroweak hierarchy problem. By definition, dark sectors are not charged under any of the known forces. Discovering their possible existence is thus challenging. I will describe how a a broad program combining particle, nuclear and atomic physics experiments can effectively probe a large region of the parameter space. I will show how the unique signatures of such physics can already be searched for with existing/planned experiments, including neutrino-proton fixed-target experiments and precision atomic measurements.

  48. RIKEN Lunch Seminar/Special Nuclear Theory Seminar

    "Neutrino Scattering on Quantum Computers"

    Presented by Alessandro Roggero, University of Washington

    Thursday, July 19, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Rob Pisarski

  49. Physics Summer School

    "Silicon detectors"

    Presented by Gabriele Giacomini

    Thursday, July 19, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai and Anze Slosar

  50. Environmental & Climate Sciences Department Seminar

    "Invariant and insensitive: climate model microphysics as a scaling problem"

    Presented by Mikael Witte, National Center for Atmospheric Research

    Thursday, July 19, 2018, 11 am
    Conference Room Bldg 815E

    Hosted by: Yangang Liu

    Clouds are inherently multiscale phenomena: the particles that make up clouds are typically microns to millimeters, while the large-scale circulations that drive cloud systems can be hundreds of kilometers across. Limited computational power and the need to accurately represent the large-scale circulations in numerical simulations of the atmosphere make explicit inclusion of cloud microphysics a practical impossibility. In the last 20 years there has been a shift toward representing microphysics as scale-aware processes. Despite this shift, many unanswered questions remain regarding the scaling characteristics of microphysical fields and how best to incorporate that information into parameterizations. In this talk, I will present results from analysis of high frequency in situ aircraft measurements of marine stratocumulus taken over the southeastern Pacific Ocean aboard the NCAR/NSF C-130 during VOCALS-REx. First, I will show that cloud and rain water have distinct scaling properties, indicating that there is a statistically and potentially physically significant difference in the spatial structure of the two fields. Covariance of cloud and rain is a strong function of length/grid scale and this information can easily be incorporated in large-scale model parameterizations. Next I will show results from multifractal analysis of cloud and rain water to understand the spatial structure of these fields, the results of which provide a framework for development of a scale-insensitive microphysics parameterization. Finally, I compare observed microphysical scaling properties with those inferred from large eddy simulations of drizzling stratocumulus, applying the same analyses as applied to the aircraft observations. We find that simulated cloud water agrees well with the observations but the drizzle field is substantially smoother than observed, which has implications for the ability of limited-area models to adequately reproduce the spatial structure o

  51. Condensed-Matter Physics & Materials Science Seminar

    "Mechanism of strange metal and strange metal state near a heavy fermion quantum critical point"

    Presented by Chung-Hou Chung, Department of Electrophysics, National Chiao-Tung University, Taiwan

    Wednesday, July 18, 2018, 1:30 pm
    ISB Bldg. 734 Conference Room 201

    Hosted by: Alexei Tsvelik

    Strange metal (SM) behaviors with non-Fermi liquid (NFL) properties, generic features of heavy fermion systems near quantum phase transitions, are yet to be understood microscopically. A paradigmatic example is the magnetic field-tuned quantum critical heavy fermion metal YbRh2Si2 (YRS), revealing a possible SM state over a finite range of fields at low temperatures when substituted with Ge. Above a critical field, the SM state gives way to a heavy Fermi liquid with Kondo correlation. The NFL behavior shows most notably a linear-in-temperature electrical resistivity and a logarithmic-in-temperature followed by a power-law-in-temperature in the specific heat coefficient at low temperatures [1]. We propose a mechanism to explain it: a quasi-2d fluctuating anti-ferromagnetic short-range resonating-valence-bond (RVB) spin-liquid competing with the Kondo correlation (Fig. 1) [2]. Applying renormalization group analysis on an effective field theory beyond a large-N approach to an antiferromagnetic Kondo-Heisenberg model, we identify the critical point, and explain remarkably well the SM behavior. Our theory goes beyond the well-established framework of quantum phase transitions and serves as a new basis to address open issues of the non-Fermi liquid behavior in quantum critical heavy-fermion compounds, such as: the strange superconductivity observed in the "115" family CeMIn5 (M=Co, Rh)[3]. References: [1] J. Custers et al., Nature 424, 524 (2003); J. Custers et al., Phys. Rev. Lett. 104, 186402 (2010). [2] Yung-Yeh Chang, Silke Paschen, and Chung-Hou Chung, Phys. Rev. B 97, 035156 (2018). [3] Y. Y. Chang,, F. Hsu, S. Kirchner, C. Y. Mou, T. K. Lee and C. H. Chung (un-published).

  52. C-AD Accelerator Physics Seminar

    "Coherent THz Radiation from Plasma Oscillation Driven by Laser Pulses"

    Presented by Dr. Min Sup Hur, Physics Department - UNIST Korea

    Tuesday, July 17, 2018, 4 pm
    Bldg. 911B, 2nd floor - Large Conference Room

    Hosted by: Dr. Bingping Xiao

    Plasma, a gas of electric charges, exhibits a fundamental oscillating behavior, the plasma oscillation. Similar to the classical harmonic oscillator, but charged, the plasma oscillation is potentially an outstanding source of coherent, monochromatic radiation with high intensity and high frequency. However, harnessing the plasma oscillation and taking the radiation out of it are never trivial problems. In this presentation, I introduce one novel method to generate an isolated plasma dipole oscillation by colliding laser pulses in a plasma, eventually to obtain a quasi-narrowband, powerful THz emission. The conceptual connection of the idea to the astrophysical plasma emission is also addressed.

  53. Physics Summer School

    "Physics Summer School: Introduction to Statistics for Particle Physics"

    Presented by Xin Qian, Brookhaven Lab

    Tuesday, July 17, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai & Anze Slosar

  54. Nuclear Theory/RIKEN Seminar

    "Confronting hydrodynamic predictions with Xe-Xe heavy-ion collision data"

    Presented by Matt Luzum, Univeristy of Sao Paulo

    Friday, July 13, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    Comparing collision systems of different size, at near the same collision energy, offers us the opportunity to probe the scaling behavior and therefore the nature of the system itself. Recently, we made predictions for Xe-Xe collisions at 5.44 TeV using viscous hydrodynamic simulations, noting that the scaling from the larger Pb-Pb system is rather generic, and arguing that robust predictions can be made that do not depend on details of the model. Here we confront our predictions with measurements that were subsequently made in a short Xe-Xe run at the LHC by the ALICE, ATLAS, and CMS collaborations. We find that the predictions are largely confirmed, with small discrepancies that could point the way to a better understanding of the medium created in such collisions.

  55. Physics Summer School

    "Intro to neutrino physics"

    Presented by Mary Bishai, BNL

    Thursday, July 12, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai and Anze Slosar

  56. RIKEN Lunch Seminar

    "Topological structures in finite temperature QCD"

    Presented by Rasmus Larsen, BNL

    Thursday, July 12, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

    We report our study on the properties of the topological structures present in the QCD medium. We use dynamical domain wall fermion configurations on lattices of size 32^3x8 and detect the topological structures through the zero modes of the overlap operator. We explicitly show that the properties of the zero modes of the QCD Dirac operator agrees well with that of calorons with non-trivial holonomy. Different profiles of the zero modes are observed, ranging from solutions that are localized in all four spacetime dimensions, to profiles that are localized in the spatial directions, and constant along the temporal extent of the lattice. This indicates towards the presence of instanton-dyons in the hot QCD medium around Tc, where the distance between dyons control the shape and extent of the zero modes.

  57. Condensed-Matter Physics & Materials Science Seminar

    "Electron-microscopy-guided designing of ferroelectric materials for nonvolatile memories and multifunctional nanodevices"

    Presented by Linze Li, University of California @ Irvine

    Thursday, July 12, 2018, 11 am
    Bldg. 480, Conference Room

    Hosted by: Yimei Zhu

    As a prototypical example of functional oxides, ferroelectric materials have been utilized in a broad range of electronic, optical, and electromechanical applications and hold the promise for the design of future high-density nonvolatile memories and multifunctional nanodevices. The utilities of ferroelectrics are derived from the structures and switching of ferroelectric domains, or from their coupling to other material functionalities. In recent years, advanced imaging techniques based on aberration-corrected scanning transmission electron microscopy (STEM) and in situ transmission electron microscopy (TEM) have become powerful methods to characterize ferroelectric oxides, allowing nanoscale polarization states to be unambiguously determined with sub-Angstrom resolution, and allowing domain switching processes to be directly resolved in real time. In this presentation I will show several examples of applying advanced STEM or TEM-based techniques to the study of the static and dynamic properties of domains and domain walls in ferroelectric and multiferroic BiFeO3 thin films. Atomic structures and electrical switching behaviors of charged domain walls have been observed. A strong interaction between the ferroelectric polarization and nanoscale impurity defects has been discovered, and a new route to the production of exotic polarization states by utilizing such interaction has been proposed and established. These findings open up the possibility for the designing of novel ferroelectric materials and multifunctional devices with nanoscale structural defects or charged domain walls as essential components.

  58. Physics Summer School

    "Introduction to flavor physics"

    Presented by Bilas Pal, BNL

    Tuesday, July 10, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai and Anze Slosar

  59. Joint Nuclear Physics and High Energy Physics Seminar

    "Parity-Violating and Parity-Conserving Asymmetries in ep and eN Scattering in the Qweak Experiment"

    Presented by Wouter Deconinck, College of William & Mary

    Tuesday, July 10, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Jin Huang

    The Standard Model provides the current best description of fundamental particles and forces, but among other limitations it fails to account for dark matter which could manifest itself as more massive particles. Precision measurements of well predicted observables in the Standard Model allow for highly targeted tests for physics beyond the Standard Model. The Qweak experiment at Jefferson Lab has made the first precise determination of the weak charge of the proton in elastic scattering of longitudinally polarized electrons from unpolarized protons. To achieve the required precision to measure the small parity-violating asymmetry of -226.5 ± 9.3 parts per billion, we directed a high current polarized electron beam on a liquid hydrogen target and integrated scattered events in eight azimuthally symmetric fused silica Cerenkov detectors. We find a value for the weak charge of proton of 0.0719 ± 0.0045, in agreement with predictions of the Standard Model. This result rules out leptoquark masses below 2.3 TeV and excludes generic new semi-leptonic parity-violation physics beyond the Standard Model below 3.5 TeV. To correct for the contributions from background processes, we conducted several additional parity-violating and parity-conserving asymmetry measurements with different kinematics (elastic and through the production of a Delta resonance), polarization (longitudinal and transverse), and targets (protons, electrons, aluminum, and carbon). I will discuss the results of the main experiment and highlight several ancillary results of interest to experiments at future facilities.

  60. Office of Educational Programs Event

    "High School Research Program Begins"

    Monday, July 9, 2018, 8 am
    Berkner Hall Auditorium

    Hosted by: Aleida Perez

  61. Physics Summer School

    "TBA"

    Thursday, July 5, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai and Anze Slosar

  62. HET Special Seminar

    "Charting the Unknown with Theory and Experiments"

    Presented by Duccio Pappadopulo, NYU

    Tuesday, July 3, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  63. Physics Summer School

    "Cosmology with Ground-Based Optical Surveys"

    Presented by Erin Sheldon, BNL

    Tuesday, July 3, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Mary Bishai and Anze Slosar

  64. Condensed-Matter Physics & Materials Science Seminar

    "Room-temperature magnetic spiral order induced by disorder"

    Presented by Christopher Mudry, Paul Scherrer Institut, Switzerland

    Monday, July 2, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Alexei Tsvelik

    Upon cooling, the compound YBaCuFeO5 undergoes a phase transition to an antiferromagnetic long-range ordered phase. Upon further cooling, a second phase transition to a magnetic spiral phase takes place. The latter transition temperature depends on the sample preparation and can reach room temperature. We propose a mechanism to explain the transition to a magnetic spiral ordered phase due to frustrating magnetic interactions that are introduced randomly along a single crystallographic direction as caused by a particular type of chemical disorder. This mechanism could open the way to high-temperature multiferroism.

  65. HET Lunch Discussions

    "Pion-pion scattering with physical quark masses from lattice QCD"

    Presented by Dan Hoying, UConn

    Friday, June 29, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  66. NSLS-II Friday Lunchtime Series

    "Investigating slow kinetic processes using synchrotron radiation: A case study of cement hydration in nuclear waste cements"

    Presented by Claire L. Corkhill, University of Sheffield, United Kingdom

    Friday, June 29, 2018, 12 pm
    NSLS-II Bldg. 743 Room 156

    Hosted by: M. Abeykoon, S. Chodankar, B. Ocko, J. Thieme, G. Wang

  67. Particle Physics Seminar

    "First results from PROSPECT: The Precision Reactor Oscillation & Spectrum experiment"

    Presented by David Jaffe, BNL

    Thursday, June 28, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    PROSPECT is a short-baseline reactor antineutrino experiment designed to search for eV-scale sterile neutrino oscillations and measure the 235U antineutrino energy spectrum from the High Flux Isotope Reactor at Oak Ridge National Laboratory. Deployed in early 2018, the 4ton, segmented, 6Li-loaded liquid scintillator detector began commissioning in March of this year. The detector consists of 154 segments that span a baseline of 7-9m from the compact highly enriched uranium core, enabling coverage of a wide range of oscillation parameter space. Full-scale prototypes have demonstrated excellent energy resolution and pulse-shape discrimination that will reject cosmogenic backgrounds and produce an unparalleled measurement of the 235U antineutrino spectrum. The first results of PROSPECT on sterile neutrino oscillations will be presented.

  68. HET Seminar

    "Constraining Effective Field Theories with Machine Learning"

    Presented by Johann Brehmer, New York University

    Wednesday, June 27, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

    An important part of the LHC legacy will be precise limits on indirect effects of new physics, parameterized for instance in an Effective Field Theory (EFT). But measuring these parameters in complex processes is often challenging for established analysis methods. We present powerful new inference techniques based on machine learning. They scale well to complicated problems with many parameters and observables and do not require any approximations on the parton shower or detector effects. In an example analysis of WBF Higgs production we show that they enable us to put stronger bounds on EFT parameters than established methods, demonstrating their potential to improve the new physics reach of the LHC legacy results. We also comment on the application of these new "likelihood-free" or "simulator-based" inference techniques to a broad class of problems outside of particle physics, for instance in cosmology, epidemiology, and genetics.

  69. Condensed-Matter Physics & Materials Science Seminar

    "Imaging of Local Structure and Dynamics in Hard and Soft Condensed Matter Systems"

    Presented by Dmitry Karpov, New Mexico State University

    Friday, June 22, 2018, 1:30 pm
    ISB Bldg. 734, Conf. Rm. 201 (upstairs)

    Hosted by: Ian Robinson

    With advancement of coherent probes there is a shift from integral studies to highly localized studies in either spatial or temporal domains. Nanostructures and low dimensional phenomena, correlated fluctuations and associated transitions directly benefit from new instrumental capabilities. Studies of ferroelectric and magnetic materials and of their local behavior allow both to test fundamental physics concepts and provide access to technologies with direct practical applications. Topological phase transitions and topological defects are among the topics that are actively pursued in modern materials science. In recent study [1] conducted by our group we were able to visualize three-dimensional topological vortex structure in a volume of individual ferroelectric nanoparticle of barium titanate under external electric field using Bragg coherent diffractive imaging technique. Among other things we observed: (i) electric field induced structural transition from mixture of tetragonal and monoclinic phases to dominant monoclinic phase; (ii) controllable switching of vortex chirality; (iii) vortex mediated behavior of the nano-domains in the particle; (iv) and that the core of the vortex in the volume behaves as a nanorod of zero ferroelectric polarization which can be rotated by external electric field and can serve as a conducting channel for charge carriers. These findings can be used in the design of novel nanoelectronics devices and for creating artificial states of matter. Better understanding of the materials behavior at the nanoscale requires ways of probing anisotropies of the refractive index. Using polarized laser light, we've developed a method [2] termed birefringent coherent diffractive imaging that allows to extract projections of dielectric permittivity tensor in nematic liquid crystal. Further expanding this tool into full-vectorial mode shows that the method can be applied for imaging of magnetic domains, cellular structures, and ot

  70. Condensed-Matter Physics & Materials Science Seminar

    "Theories of transport scaling in disordered semimetals and topological spin-nematic excitonic insulators in graphite under high magnetic field"

    Presented by Ryuichi Shindo, Peking University, China

    Thursday, June 21, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Alexei Tsvelik

    In the first part of my talk, I will talk about transport scaling theories in disordered Weyl semimetal [1,2]. In electronic band structure of solid state material, two band touching points with linear dispersion (called as `Weyl node') appear in pair in the momentum space. When they annihilate with each other, the system undergoes a quantum phase transition from Weyl semimetal (WSM) phase to a band insulator (BI) phase. The continuous phase transition is recently discovered in solid state materials [3]. The phase transition is described by a critical theory with a `magnetic dipole' like object in the momentum space. The critical theory hosts a disorder-driven quantum multicritical point, which is encompassed by three quantum phases, WSM phase, BI phase, and diffusive metal (DM) phase. Based on the renormalization group argument, we clarify transport scaling properties around the Weyl node at the quantum multicritical point as well as all phase boundaries among these three phases [1,2]. In the second part of my talk, I will argue that three-dimensional topological excitonic insulator is realized in graphite under high magnetic field [4,5]. Graphite under high magnetic field exhibits consecutive metal-insulator (MI) transitions as well as re-entrant insulator-metal (IM) transition at low temperature. We explain these enigmatic insulator phases as manifestation of excitonic insulator phases with spin nematic orderings ("SNEI" phases). Especially, we explain unusual field-dependences of in-plane resistivity in the graphite experiment by surface transports via 2+1 massless surface Dirac fermion in one of the SNEI phases [4,5]. [1] https://arxiv.org/abs/1803.09051, under review [2] https://arxiv.org/abs/1710.00572, selected as PRB editors' suggestion [3] Tian Liang, et.al., Science Advances, 3, e1602510 (2017) [4] https://arxiv.org/abs/1802.10253, under review [5] in preparation &

  71. Physics Summer School

    "Physics Summer School: Why we need physics beyond the Standard Model"

    Presented by Hooman Davoudiasl, BNL

    Thursday, June 21, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai and Anze Slosar

  72. Condensed-Matter Physics & Materials Science Seminar

    "Fermi-Surface Reconstruction in Nd-doped CeCoIn5"

    Presented by Elizabeth Green, Dresden High Magnetic Field Laboratory

    Thursday, June 21, 2018, 11 am
    ISB Bldg. 734 Seminar Room 201 (upstairs)

    Hosted by: Cedomir Petrovic

    Heavy fermion compounds are well known to exhibit novel properties when exposed to high magnetic fields. Most notably CeCoIn5 exhibits a field-induced superconducting state at high magnetic fields known as the Qphase. Recent neutron scattering measurements show a similar Q-vector for the 5% Nd-doped CeCoIn5 at zero applied magnetic field [1] which has initiated intense theoretical and experimental work on this doping series. In this talk I will present de Haas-van Alphen effect measurements which indicate a drastic Fermi-surface reconstruction occurs between 2 and 5% Nd-doping levels. The cylindrical Fermi surface, believed to play a crucial role in superconductivity in these materials, develops a quasi-three-dimensional topology with increased doping levels thus reducing the likelihood of an enhanced nesting scenario, previously given as a possible explanation for the Q-phase. However, effective masses remain relatively unchanged up to 10% Nd indicating the crossing of a spin density wave type of quantum critical point. In addition, I will present evidence that by substituting Ce with Nd the electronic pairing potential may be altered. These results help elucidate the reasoning for the emergence of the Q-phase seen in the 5% Nd sample and may be relevant to other heavy fermion compounds. [1] S. Raymond et al., JPSJ 83, 013707 (2014).

  73. Physics Colloquium

    "Subatomic Swirls and Massive Magnetic Fields - Lambda Polarization in Heavy Ion Collisions at RHIC"

    Presented by Michael Lisa, Ohio State University

    Tuesday, June 19, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    Last year, the STAR Collaboration at RHIC published the first observation of global hyperon polarization in heavy ion collisions. This polarization may be used to extract rotational substructure of the flow field. The result represented a striking validation of the near-equilibrium hydrodynamic paradigm and established the quark-gluon plasma at RHIC as by far the most vortical fluid in nature. More recent studies quantify the vortical structure systematics to challenge hydro models in detail. In addition to the rotational fluid substructure, hyperon polarization should probe the strong magnetic fields expected in heavy ion collisions. Measuring these fields is crucial for establishing and quantifying the so-called Chiral Magnetic Effect at RHIC. Experimental uncertainties are currently too large to conclusively measure the magnetic field, but detector upgrades at STAR and dedicated running at RHIC may allow a breakthrough in this year's (2018) run.

  74. Condensed-Matter Physics & Materials Science Seminar

    "X-ray Scattering as a Tool for Understanding Nanostructured Materials"

    Presented by Robert Koch, Alfred University

    Tuesday, June 19, 2018, 1:30 pm
    ISB Bldg. 734, Conf. Rm. 201 (upstairs)

    Hosted by: Ian Robinson

    Materials with significant local distortions from the bulk average structure often show novel and useful properties. Identifying and quantifying the nature and extent of this correlated disorder1 is however quite challenging, as traditional crystallography and the associated tools often do not adequately describe such nanostructured materials. This is a manifestation of the "nanostructure problem"2 and the solution requires complex modelling incorporating multiple techniques. This talk focuses on the application of X-ray scattering and complex modelling as tools for understanding various nanostructured materials, including nanocrystalline nickel with large clusters of planar defects, interlayered non-silicon photovoltaics, geometrically frustrated ternary alkaline earth hexaborides, manganese dioxide nanosheet assemblies, and nanostructured noble metal alloys. Complex modelling leveraging both standard techniques as well as genetic algorithms, Markov chain Monte Carlo, and machine learning together provide synergistic understanding spanning length scales from a few Ångstrom to hundreds of nanometers. Additionally, an example of how complex modelling can be used to shed understanding on the nature of crystallographic disorder in superconducting alloys of 2H-TaSe2−xSx is discussed. A potential model is proposed whereby alloys of 2H-TaSe2−xSx are composed of interlayered sheets with two unique c-axes. This model is consistent with the observed 00l Bragg profile broadening trend and may help explain the suppression of charge density waves and maximization of superconductivity in these systems. 1. Keen, D. A. & Goodwin, A. L. The crystallography of correlated disorder. Nature 521, 303–309 (2015). 2. Billinge, S. J. L. & Levin, I. The problem with determining atomic structure at the nanoscale. Science 316, 561–565 (2007).

  75. Physics Summer School: Introduction to Particle Physics

    Presented by Bill Morse, BNL

    Tuesday, June 19, 2018, 12:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mary Bishai and Anze Slosar

  76. Nuclear Physics Seminar

    "Measurements of charm, bottom, and Drell-Yan via dimuons in p+p and p+Au collisions at sNN=200 GeV with PHENIX at RHIC"

    Presented by Yue Hang Leung, Stonybrook University

    Tuesday, June 19, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Jin Huang

    Dilepton spectra are a classic probe to study ultra-relativistic heavy ion collisions. At RHIC energies, the dimuon continuum is dominated by correlated pairs from charm and bottom semi-leptonic decays and the Drell-Yan process. In this talk, we present measurements of µµ pairs from charm, bottom, and Drell-Yan in p+p and p+Au collisions at sNN = 200 GeV. Differential yields from charm and bottom in p+p collisions will be presented and implications for the relative contributions from different heavy flavor production mechanisms will be discussed. We will also present results of bottom yields in p+Au collisions and discuss the implications on cold nuclear matter effects. This study also enables first measurements of the Drell-Yan cross-section at s_{NN} = 200 GeV. Studying Drell-Yan production in p+Au collisions is a clean probe for modifications of the initial state. The Drell-Yan differential cross-sections in p+p collisions and progress on p+Au collisions will be presented.

  77. HET Lunch Discussions

    "Discussion of Mainz workshop of g-2 Theory Initiative"

    Presented by Mattia Bruno and Aaron Meyer, BNL

    Friday, June 15, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  78. Particle Physics Seminar

    "Jet substructure in ATLAS at the LHC – a tool for discoveries and measurements"

    Presented by Peter Loch, University of Arizona

    Thursday, June 14, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    The ATLAS experiment at the Large Hadron Collider (LHC) applies jet substructure analysis techniques to extract the internal energy flow in high energy jets produced in the proton-proton collisions in searches for new physics as well as in Standard Model (SM) measurements. In this talk we will introduce the most commonly applied techniques and present an overview of results from the respective performance evaluations. In addition, we will discuss selected configurations of tagging algorithms designed to extract two- or three-prong energy flow patterns inside a jet, as generated by decays of SM particles like the W-boson or the top quark, or possible new heavy particles indicating physics beyond the SM. A brief presentation of recent results from searches and SM measurements, including the recent measurement of the internal structure of light quark and gluon jets, concludes the talk.

  79. Condensed-Matter Physics & Materials Science Seminar

    "Doublon-holon origin of the subpeaks at the Hubbard band edges"

    Presented by Seung-Sup Lee, Ludwig-Maximilians-University, Germany

    Thursday, June 14, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Andreas Weichselbaum

    Dynamical mean-field theory (DMFT) studies frequently observe a fine structure in the local spectral function of the SU(2) Fermi-Hubbard model (i.e., one-band Hubbard model) at half filling: In the metallic phase close to the Mott transition, subpeaks emerge at the inner edges of the Hubbard bands. Here we demonstrate that these subpeaks originate from the low-energy effective interaction of doublon-holon pairs, by investigating how the correlation functions of doublon and holon operators contribute to the subpeaks [1, 2]. We use the numerical renormalization group (NRG) as a DMFT impurity solver to obtain the correlation functions on the real-frequency axis with improved spectral resolution [3]. A mean- field analysis of the low-energy effective Hamiltonian [2] provides results consistent with the numerical result. The subpeaks are associated with a distinctive dispersion that is different from those for quasiparticles and the Hubbard bands. Also, the subpeaks become more pronounced in the SU(N) Hubbard models for larger number N of particle flavors, due to the increased degeneracy of doublon-holon pair excitations. Hence we expect that the sub-peaks can be observed in the photoemission spectroscopy experiments of multi-band materials or in the ultracold atom simulation of the SU(N) Hubbard models. [1] S.-S. B. Lee, J. von Delft, and A. Weichselbaum, Phys. Rev. Lett. 119, 236402 (2017). [2] S.-S. B. Lee, J. von Delft, and A. Weichselbaum, Phys. Rev. B 96, 245106 (2017). [3] S.-S. B. Lee and A. Weichselbaum, Phys. Rev. B 94, 235127 (2016).

  80. Condensed-Matter Physics & Materials Science Seminar

    "Defects and their functional properties in multiferroic hexagonal systems"

    Presented by Shaobo Cheng, McMaster University Canada

    Monday, June 11, 2018, 2:30 pm
    Bldg. 480, Conference Room

    Hosted by: Yimei Zhu

    As a main component of quantum materials, multiferroic materials, which simultaneously have multiple orderings, hold promise for use in the next generation of memory devices. Taking advantage of the state-of-the-art transmission electron microscopy techniques, we have systematically studied the defects induced emergent phenomena in multiferroic hexagonal systems. Two single phase multiferroic hexagonal systems will be covered in this talk: YMnO3 and LuFe2O4. YMnO3 is a classic single phase multiferroic material with geometric ferroelectricity. The effects oxygen vacancies, partial edge dislocations, and interfacial atomic reconstructions will be presented. LuFe2O4 is a well-known multiferroic system with charge ordering origin. The effects of twins and interstitial oxygen in LuFe2O4 single crystalline sample will be discussed. The structural-property relationship for both systems has been tried to be established in our studies. Our findings demonstrate the structural flexibility of both manganites and ferrites, and open the door to new tunable multifunctional applications.

  81. Center for Functional Nanomaterials Seminar

    "Heterostructures for Nanoelectronics and Photovoltaics"

    Presented by Deep Jariwala, University of Pennsylvania

    Monday, June 11, 2018, 1:30 pm
    CFN, Bldg. 735, Conference Room A, 1st Floor

    Hosted by: Don DiMarzio & Mircea Cotlet

    The isolation of a growing number of two-dimensional (2D) materials has inspired worldwide efforts to integrate distinct 2D materials into van der Waals (vdW) heterostructures. While a tremendous amount of research activity has occurred in assembling disparate 2D materials into "all-2D" van der Waals heterostructures,1, 2 this concept is not limited to 2D materials alone. Given that any passivated, dangling bond-free surface will interact with another via vdW forces, the vdW heterostructure concept can be extended to include the integration of 2D materials with non-2D materials that adhere primarily through noncovalent interactions.3 In the first part of this talk I will present our work on emerging mixed-dimensional (2D + nD, where n is 0, 1 or 3) heterostructure devices performed at Northwestern University. I will present two distinct examples of gate-tunable p-n heterojunctions.4-6 I will show that when a single layer n-type molybdenum disulfide (MoS2) (2D) is combined with p-type semiconducting single walled carbon nanotubes (1D), the resulting p-n junction is gate-tunable and shows a tunable diode behavior with rectification as a function of gate voltage and a unique anti-ambipolar transfer behavior.4 The same concept when extended to p-type organic small molecule semiconductor (pentacene) (0D) and n-type 2D MoS2 leads to a tunable p-n junction with a photovoltaic effect and an asymmetric anti-ambipolar transfer response.6 I will present the underlying charge transport and photocurrent responses in both the above systems using a variety of scanning probe microscopy techniques as well as computational methods. Finally, I will show that the anti-ambipolar field effect observed in the above systems can be generalized to other semiconducting heterojunction systems and extended over large areas with practical applications in wireless communication circuits.5 The second part of talk will discuss my more recent work performed at Caltech on photovo

  82. Physics Colloquium

    "How we got the government we have, and why scientists should engage with it"

    Presented by Benn Tannenbaum, Sandia National Laboratory

    Tuesday, June 5, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    It seems like a terrible time to be a scientist in the United States. Federal budgets aren't being passed, and when they are, funding for science never seems to increase. The debate over immigration reform—including what to do about visas for high-skilled workers, such as scientists—is stalled. Everyone agrees that cybersecurity is a problem, but no one seems to have a solution. Meanwhile, we have no meaningful debate in Congress or in the administration on climate change or energy policy. This lecture will cover how we got here, why we are stuck, some speculation on how the current administration is impacting research, and how the scientific community can impact policy.

  83. Nuclear Theory/RIKEN Seminar

    "Liouville action, high multiplicity tail and shape of proton"

    Presented by Vladimir Skokov, BNL

    Friday, June 1, 2018, 2 pm
    CFNS Seminar Room, 2-38

    Hosted by: Chun Shen

    In this talk I violate the common wisdom "one seminar — one message" and discuss two seemingly unrelated results in the framework of the dilute-dense CGC approach: the effect of spatial eccentricity of the projectile (proton) shape on the second harmonic in double-inclusive gluon production and the theoretical description of the high gluon multiplicity tail. I will show that these two superficially unrelated results in combination may lead to unexpected consequences for the phenomenology of p-A collisions.

  84. HET Lunch Discussions

    "Nucleon Charges and Form Factors from Lattice QCD"

    Presented by Yong-Chull Jang, BNL

    Friday, May 25, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  85. Joint Nuclear Theory/RIKEN/CFNS Seminar

    "Novel QCD Physics at an Electron-Ion Collider"

    Presented by Stanley Brodsky, SLAC National Accelerator Laboratory, Stanford University

    Friday, May 25, 2018, 10:30 am
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    An electron-ion collider can test many fundamental features of QCD for hadron and nuclear physics, including flavor-dependent antishadowing in deep inelastic electron-nucleus scattering, the breakdown of sum rules for nuclear structure functions, the role of ``hidden-color " degrees of freedom, and the effects of "color transparency" on the baryon-to-meson anomaly observed at high transverse momentum in heavy-ion collisions. I will also discuss intrinsic heavy quark phenomena and the production of exotic multiquark states at the EIC. On the theory side, I will discuss the new insights into color confinement that one obtains from light-front holography, including supersymmetric features of the meson, baryon, and tetraquark spectroscopy. The Principle of Maximum Conformality (PMC) can be used to systematically eliminate renormalization scale ambiguities and thus obtain scheme-independent pQCD predictions.

  86. Particle Physics Seminar

    "K+ to pi+ nu nubar- First result from NA62 experiment"

    Presented by Bob Velghe, TRIUMF

    Thursday, May 24, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    The K+ to pi+ nu nubar decay has been attracting interest for many decades. The accurate measurement of its branching ratio is a powerful test of the Standard Model (SM) and could reveal effects beyond the SM. As the decay occurs at the level of 1 in a 10 billion kaon disintegration, many experimental challenges have to be overcome. The CERN NA62 experiment uses a novel kaon decay-in-flight technique to observe K+ to pi+ nu nubar. The analysis of the 2016 data set was used to establish the method by allowing us to reach the 10^-10 single event sensitivity. The preliminary NA62 result on K+ to pi+ nu nubar from the analysis of the full 2016 data set will be presented.

  87. Condensed-Matter Physics & Materials Science Seminar

    "Developing theoretical understanding of non-equilibrium phenomena"

    Presented by Alexander Kemper, North Carolina State University

    Thursday, May 24, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Peter D. Johnson

    In this talk, I will present an overview of some of our recent results in the area of non-equilibrium many-body theory. Experimental developments are enabling the study of electrons and atoms in the time domain with ever increasing resolution. The theoretical development has been somewhat lacking, and remains mostly rooted in extensions of equilibrium models. Our work has been to put the theoretical modeling on a firmer footing. Through numerical solution of the equations of motion, we can directly evaluate experimentally relevant spectra. These may be analyzed with the benefit of knowing the precise model and correlation functions that underlie the spectra. Most of the talk will focus on the interaction between a system of electrons interacting with several degrees of freedom, including the lattice, impurity scattering, and each other. Typically, non-equilibrium results are analyzed through a framework that relies on equilibrium intuition. Our results show that the validity of this type of analysis falls on a spectrum that varies from correct to wholly incorrect, which I will illustrate with specific examples. This line of thinking will be further developed by considering the flow of energy between various subsystems.

  88. HET Seminar

    "Towards NLO parton showers"

    Presented by Stefan Prestel, Fermilab

    Wednesday, May 23, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

    Parton showers aim to consistently model the evolution of the soft and collinear structure of QCD. As such, they are important pieces of event generator software. Parton shower methods have, since their inception, been limited to lowest order precision. For a consistent NLO event generator framework, and to reduce the uncertainties inherent in a lowest-order approach, it is important to push parton showers beyond lowest order precision. In this talk, I will discuss recent advances within the Dire parton shower (of Pythia and Sherpa) to construct a consistent NLO parton shower.

  89. Particle Physics Seminar

    "CERN openlab R&D for the LHC Run3 and Run4"

    Presented by Maria Girone, CERN

    Tuesday, May 22, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sergey Panitkin

    LHC Run3 and Run4 represent an unprecedented challenge for HEP computing in terms of both data volume and complexity. New approaches are needed for how data is collected and filtered, processed, moved, stored and analysed if these challenges are to be met with a realistic budget. To develop innovative techniques we are fostering relationships with industry leaders. CERN openlab is a unique resource for public-private partnership between CERN and leading Information Communication and Technology (ICT) companies. Its mission is to accelerate the development of cutting-edge solutions to be used by the worldwide HEP community. In 2018, CERN openlab started its phase VI with a strong focus on tackling the upcoming LHC challenges. Several R&D programs are ongoing in the R&D areas of data centre technologies and infrastructures. computing performance and software, machine learning and data analytics. This talk gives an overview of the various innovative technologies that are currently being explored by CERN openlab VI and discusses the long-term strategies that are pursued by the LHC communities with the help of industry in closing the technological gap in processing and storage needs expected in Run3 and Run4.

  90. Instrumentation Division Seminar

    "The ATLAS ITK Strip Detector for High-Luminosity LHC"

    Presented by Stefania Stucci, CERN, Italy

    Tuesday, May 22, 2018, 2:30 pm
    Large Conference Room, Bldg. 535

    The High-Luminosity LHC operations are scheduled to start in 2026. The ATLAS experiment is currently preparing for an upgrade of the inner tracking detector. The radiation damage at the maximum integrated luminosity of 4000/fb implies integrated hadron fluencies over 2x10^16 neq/cm2 requiring replacement of the existing Inner Detector. An all-silicon Inner Tracker (ITk) is proposed with a pixel detector surrounded by a strip detector. The current prototyping phase, targeting an ITk Strip Detector consisting of a four-layer central barrel and forward regions composed of six disks at each end, will be described. In this contribution I will present the design of the ITk Strip Detector and the preparations for production.

  91. HET Lunch Discussions

    "Decays of the Higgs into gauge bosons in the SMEFT at the NLO"

    Presented by Pier Paolo Giardino, BNL

    Friday, May 18, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  92. HET Seminar

    "Review of Neutral Kaon Oscillations in and beyond the Standard Model from Lattice QCD"

    Presented by Anastassios Vladikas, INFN Roma Tor Vergata

    Wednesday, May 16, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mattia Bruno

    The study of the low energy strong interaction effects in neutral K-meson oscillations is based on the lattice regularisation of QCD. Precise and consistent results for the bag parameter BK, in line with expectations from Standard Model flavour phenomenology, have been obtained over the years, from several variants of lattice QCD. More recently, a few groups have also studied BK in extensions of the Standard Model. The discrepancies seen between certain results from different groups are arguably attributed to uncontrolled systematic errors in the non-perturbative renormalisation and running of weak matrix elements. The Schroedinger Functional renormalisation scheme may help resolve these discrepancies.

  93. Physics Colloquium

    "Driven Quantum and Dirac Matter"

    Presented by Alexander Balatsky, Los Alamos

    Tuesday, May 15, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

  94. Nuclear Physics Seminar

    "TMD evolution as a double-scale evolution"

    Presented by Alexey Vladimirov, Universitat Regensburg

    Tuesday, May 15, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Oleg Eyser

    Transverse momentum dependent (TMD) distributions depend on the pair of scaling parameters and their evolution is given by a pair of coupled equations. I present the analysis of the TMD evolution equations and their solution with the emphasis on their two-dimensional structure. It results in a new viewpoint on TMD evolution, both from the technical and interpretation sides. I formulate the non-perturbative definition of zeta-prescription and introduce the notion of optimal TMD distribution. I demonstrate that the updated form of TMD evolution produces lesser theoretical uncertainty and improves agreement with the data.

  95. HET/RIKEN Lunch Discussions

    "Localized 4-Sigma and 5-Sigma Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events"

    Friday, May 11, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Co-hosted by Christoph Lehner and Taku Izubuchi

  96. HET/RIKEN Lunch Seminar

    "Quantum Simulation from Quantum Chemistry to Quantum Chromodynamics"

    Presented by Peter Love, Tufts

    Thursday, May 10, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Mattia Bruno and Enrico Rinaldi

    Quantum simulation proposes to use future quantum computers to calculate properties of quantum systems. In the context of chemistry, the target is the electronic structure problem: determination of the electronic energy given the nuclear coordinates of a molecule. Since 2006 we have been studying quantum approaches to quantum chemical problems, and such approaches must face the challenges of high, but fixed, precision requirements, and fermion antisymmetry. I will describe several algorithmic developments in this area including improvements upon the Jordan Wigner transformation, alternatives to phase estimation, adiabatic quantum computing approaches to the electronic structure problem, methods based on sparse Hamiltonian simulation techniques and the potential for experiments realizing these algorithms in the near future. I will also briefly review work by others on the analog and digital simulation of lattice gauge theories using quantum simulators.

  97. Physics Colloquium

    "The Cosmic Microwave Background and How It Keeps on Revealing More about the Universe"

    Presented by Suzanne Staggs, Princeton

    Tuesday, May 8, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    In the 50+ years since its discovery, the cosmic microwave background (CMB) has yielded surprisingly detailed and precise information about the form, content and dynamics of the early universe. High angular resolution maps, and polarization data at all angular scales, are the focus of current and next-generation instruments. I will describe what we already know about the universe from the CMB, and lay the ground for future revelations from the CMB, with special emphasis on the Atacama Cosmology Telescope (ACT). ACT is a special-purpose 6m telescope situated at 17,000 ft in the dry Atacama Desert of northern Chile, at a latitude of 23 degrees South. ACT's millimeter-wave detectors measure both polarization and intensity at very fine angular scales (arcminutes). I will describe the ACT instrument and its data in the context of other ongoing and proposed CMB projects, their scientific impact, and the potential discovery space. I will include a brief description of the upcoming Simons Observatory.

  98. Condensed-Matter Physics & Materials Science Seminar

    "Picoastronomy: an electron microscopist's view of the history of the Solar System"

    Presented by Rhonda Stroud, US Naval Research Laboratory

    Friday, May 4, 2018, 2 pm
    Bldg. 480, Conference Room

    Hosted by: Yimei Zhu

    A wide range of astrophysical processes, from condensation of dust particles in circumstellar envelopes to space weathering on airless bodies, are inherently pico-to-nanoscale phenomena. Thus an electron microscope, used for direct observation of planetary materials in the laboratory, can be as much of an astronomical tool as a telescope pointed at the sky. The energy resolution of state-of-the-art monochromated scanning transmission electron microscopes (STEMs), as low as 10 meV, makes it possible to directly observe the infra-red optical properties of individual cosmic dust grains in the 5 to 25 um range. Thus, distinguishing the 10-um and 18-um features of individual bonafide astrosilicates is now possible. The identity of volatiles, trapped in individual nanoscale vesicles, can be determined with STEM-EELS to better constrain space weathering processes in lunar soils. Finally, STEM-EDS offers to possibility of constraining noble gas contents of primitive carbonaceous materials, including nanodiamond, and "phase Q", thus thus constrain their formation histories.

  99. HET Lunch Discussions

    "Variation of alpha from a long range force"

    Presented by Hooman Davoudiasl, BNL

    Friday, May 4, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  100. Particle Physics Seminar

    "Beam Dynamics Measurements for the Muon g-2 Experiment at Fermilab"

    Presented by Dr. Tammy Walton, Fermilab

    Thursday, May 3, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    There exists a > 3 sigma discrepancy between the experimental measurement and Standard Model prediction of the anomalous magnetic moment for the muon. The Muon g-2 experiment at Fermilab will reduce the experimental uncertainty of 540 ppb to 140 ppb, which includes improving the systematic uncertainty by a factor of 3. A significant reduction in the systematic uncertainty for sources associated with the dynamics of the muon beam are needed in order to achieve the expected goal. The experiment is operational and accumulating physics data. The presentation focus on measuring the spatial distribution and dynamics of the muon beam using high advanced tracking detectors. In addition, beam dynamics measurements using other detector systems are presented. By taking advantage of the different detector systems, the Fermilab's experiment is highly equipped to control the various sources contributing to the muon beam-related uncertainties.

  101. Physics Colloquium

    "The Muon g-2 Experiment at Fermilab"

    Presented by Tammy Walton, FNAL- Leona Woods Lectureship award winner's colloquium

    Tuesday, May 1, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    The Muon g-2 experiment at Fermilab is measuring the anomalous magnetic dipole moment of the muon with an improved factor of four accuracy (140 ppb). The new measurement is inspired by the > 3s discrepancy between the Brookhaven experimental measurement and Standard Model prediction, where the discrepancy gives hints of new physics beyond the Standard Model. The Fermilab's Muon g – 2 experiment is taking physics data and is projected to accumulate 1 x BNL statistics by the end of the spring 2018 Fermilab's accelerator shutdown. In this presentation, I will discuss the scientific motivation and physics of muon g – 2 experiments and conclude with a snapshot of data results from the beginning of the physics run.

  102. Condensed-Matter Physics & Materials Science Seminar

    "Chemistry beyond the crystal- advanced Fourier techniques"

    Presented by Simon Kimber, Oak Ridge National Laboratory

    Monday, April 30, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Ian Robinson

    Chemical crystallography nowadays makes structure determination and refinement trivial. However, advances in x-ray and neutron sources mean that we should revisit some of the basic assumptions that shape our experiments. For example, most chemical reactivity in e.g. catalysis, self-assembly etc, occurs in the solution phase. Why are we as crystallographers then wedded to the solid state? In this presentation, I will show how total scattering can be used to determine changes in cluster structure during photochemical reactions and to probe the role of the solvent in 'magic size' cluster formation. I will then describe how neutron scattering techniques can be used to challenge another basic assumption- the static approximation in total scattering. We have successfully applied so-called 'dynamic-PDF' techniques to simple chalcogenide materials. This allows to determine the time scale on which local distortions appear, providing insight into the role of highly anharmonic phonons in e.g. phase change and thermoelectric materials. Time allowing, I will also provide a short update on progress at ORNL, including the upcoming restart of the SNS, and new instrumentation for diffraction, total and diffuse scattering.

  103. Nuclear Theory/RIKEN Seminar

    "Exploring the QCD phase structure with functional methods"

    Presented by Bernd-Jochen Schaefer, University of Giessen

    Friday, April 27, 2018, 2 pm
    Building 510, CFNS Seminar Room 2-38

    Hosted by: Chun Shen

    QCD at finite temperature and moderate densities predicts a phase transition from a chiral symmetry broken hadronic phase to a chirally restored deconfined quark-gluon plasma phase. In this talk I report on recent progress achieved basically with functional renormalization group (FRG) methods to reveal the QCD phase structure. Two and three quark flavor FRG investigations are confronted to results obtained with effective chiral low-energy models. The importance of quantum and thermal fluctuations is demonstrated and their consequences for the experimental signatures to detect possible critical endpoints in the phase diagram are discussed.

  104. HET Lunch Discussions

    "Revisiting the Dark Photon Interpretation of the Muon g-2 Anomaly"

    Presented by Gopolang Mohlabeng, BNL

    Friday, April 27, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  105. CFNS Seminar

    "Polarized light ion physics with spectator tagging at EIC"

    Presented by Christian Weiss, Jefferson Lab

    Thursday, April 26, 2018, 4 pm
    CFNS Seminar Room, Bldg. 510, Room 2-38

    Hosted by: Andrey Tarasov

    Measurements of deep-inelastic scattering (DIS) on polarized light ions (deuteron, 3He, ...) address important physics topics such as the spin structure of the neutron, nuclear modifications of parton densities, and coherent effects at small x. Detection of the nuclear breakup state ("spectator tagging") reveals the nuclear configurations present during the high-energy process and permits a controled theoretical treatment of nuclear effects. We report about an on-going effort to develop the theoretical and experimental methods for spectator tagging with the deuteron at EIC. This includes (a) the description of nuclear structure and breakup in DIS using methods of light-front quantization; (b) extraction of free neutron spin structure from tagged DIS using on-shell extrapolation; (c) novel studies of nuclear shadowing in diffractive tagged DIS at small x; (d) the forward detector and ion beam requirements for spectator tagging at EIC. We present suggestions for future physics studies and detailed process simulations.

  106. Joint BNL/SBU HET Seminar

    "Mining the LHC Data for Anomalies"

    Presented by Matthew Buckley, Rutgers University

    Wednesday, April 25, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

  107. Condensed-Matter Physics & Materials Science Seminar

    "Topological properties of Weyl semimetals in the presence of randomness"

    Presented by Jedediah Pixley, Rutgers

    Wednesday, April 25, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Laura Classen

    We will discuss the effects of short-range disorder on three-dimensional Weyl semimetals with a focus on the topological Fermi arc surface states and the existence of the axial anomaly in the presence of parallel electric and magnetic fields. We will briefly review the bulk properties of disordered Weyl semimetals concentrating on the proposed quantum critical point separating a semimetal and diffusive metal phase driven by disorder. We show that quasi-localized, rare eigenstates contribute an exponentially small but non-zero density of states at the Weyl node energy. This destabilizes the semimetal phase and converts the semimetal-to-diffusive metal transition into a cross over (dubbed an avoided quantum critical point). In turn, it is no longer obvious how robust the topological properties are in these materials. We will therefore discuss the effects disorder has on the robustness of Weyl Fermi arc surface states and the axial anomaly. We find that the Fermi arcs, in addition to having a finite lifetime from disorder broadening, hybridize with the non-perturbative bulk rare states, which unbinds them from the surface (i.e. they lose their purely surface spectral character). Nonetheless, the surface chiral velocity is robust and survives in the presence of strong disorder. Lastly, we will discuss the robustness of the axial anomaly for a single Weyl cone in the presence of disorder. We will show that deep in the diffusive limit, when a band structure picture of dispersing (chiral) Landau levels no longer applies, the axial anomaly survives.

  108. Physics Colloquium

    "Nature vs. Nurture in Complex (and Not-So-Complex) Systems"

    Presented by Daniel Stein, NYU

    Tuesday, April 24, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    Understanding the dynamical behavior of many-particle systems following a deep quench is a central issue in both statistical mechanics and complex systems theory. One of the basic questions centers on the issue of predictability: given a system with a random initial state evolving through a well-defined stochastic dynamics, how much of the information contained in the state at future times depends on the initial condition (``nature'') and how much on the dynamical realization (``nurture'')? We discuss this question and present both old and new results for both homogeneous and random systems in low and high dimension.

  109. Condensed-Matter Physics & Materials Science Seminar

    "Building and understanding magnetic nano-structures, one atom at a time"

    Presented by Adrian Feiguin, Northeastern University

    Tuesday, April 24, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Alexei Tsvelik

    In the past decade we have witnessed enormous progress in experiments that consist of placing magnetic atoms at predetermined positions on substrates and building magnetic nanostructures one atom at a time. The effective interaction between spins is mediated by the conduction electrons in the substrate. In order to understand these interactions, we rely on a theory developed decades ago by Ruderman, Kittel, Kasuya, and Yosida, dubbed "RKKY theory", which applies when the spins are classical. The quantum nature of the electronic spin introduces another degree of complexity and competition with another quantum phenomenon: the Kondo effect. This competition is quite subtle and non-trivial, and can only be studied by numerical means. We investigate this mechanism on different lattice geometries in 2 and 3 dimensions by introducing an exact mapping onto an effective one-dimensional problem that we can solve with the density matrix renormalization group method (DMRG). We show a clear and departure from the conventional RKKY theory, and important differences that can be attributed to the dimensionality and geometry. We have found that there is a critical distance at which the Kondo effect dominates, translating into a finite range for the RKKY interaction. In particular, for dimension d>1, Kondo physics dominates even at short distances, while the ferromagnetic RKKY state is energetically unfavorable. Remarkably, in the case of impurities with higher spin S=1, both effects can co-exist: while the impurities are partially screened by the conduction electrons, an effective dangling spin S=1/2 is responsible for the entanglement between impurities.

  110. Nuclear Physics Seminar

    "Fictions, fluctuations and mean fields"

    Presented by Pasi Huovinen, Uniwersytet Wroclawski

    Tuesday, April 24, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Oleg Eyser

    The difference between fluctuations and correlations as calculated using lattice QCD from the values evaluated using hadron resonance gas model, has been taken as an indication that there must be more resonance states then observed so far. In this talk I explore how the fluctuations and correlations change if I include the unobserved states (fictions) predicted by a quark model to the hadron resonance gas, and, on the other hand, how the fluctuations and correlations change if we include the repulsive interactions between baryons and antibaryons in the hadron resonance gas model using repulsive mean field.

  111. Particle Physics Seminar

    "Signal Processing in Single-Phase LArTPCs - Application at MicroBooNE"

    Presented by Brooke Russell, Yale University, Wright Laboratory

    Thursday, April 19, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    The single-phase liquid argon time projection chamber (LArTPC) is a burgeoning detector technology with extensive use in existing and planned accelerator neutrino experiments. While engineering challenges in developing this technology have largely been overcome, high-quality reconstruction of the detailed topological and calorimetric information provided by the fine-grained drifted ionization charge signal is still in active development. In this talk, I describe a robust ionization charge extraction method developed at MicroBooNE and generically applicable to all single-phase LArTPC experiments. This technique accurately converts the raw digitized TPC waveforms into the number of ionization electrons from both induction and collection wire planes. The performance of cold electronics is critical to the success of signal extraction methods. I motivate how characterization and suppression of detector noise translates to signal processing proficiency. Finally, I relate the performance of signal processing to the context of MicroBooNE's physics goals and prospects to realize the promised capability of LArTPC detector technology.

  112. Joint BNL/SBU HET seminar

    "Neutron stars chirp about vacuum energy"

    Presented by Csaba Csaki, Cornell University

    Wednesday, April 18, 2018, 2:30 pm
    YITP

    Hosted by: Christopher Murphy

    While the current vacuum energy of the Universe is very small, in our standard cosmological picture it has been much larger at earlier epochs. We try to address the question of what are possible ways to try to experimentally verify the properties of vacuum energy in phases other than the SM vacuum. One promising direction is to look for systems where vacuum energy constitutes a non-negligible fraction of the total energy, and study the properties of those. Neutron stars could be such systems, and we discuss how to use the recent observation of neutron star mergers to try to learn about the inner core of the neutron star which may be dominated by vacuum energy.

  113. Physics Colloquium

    "Plasma science - From laboratory-fusion to astrophysical plasmas"

    Presented by Fatima Ebrahimi, Princeton Plasma Physics Laboratory and Princeton University

    Tuesday, April 17, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    Our universe is immersed in magnetized plasma, electrically conducting ionized gas. Some of the most fundamental and long-standing astrophysical problems, such as the magnetization of the universe, collimation of astrophysical jets, the accretion process and transport in astrophysical disks (surrounding e.g. black holes) and their coronas can only be explored through plasma physics. Our sun as a natural laboratory for plasma physics provides inspiring as well as challenging problems, including its dynamo cycles, heating, and the replication of its core reaction, fusion energy, on earth in a lab. There is an abundance of observational/experimental data emerging from natural phenomena of space and astrophysical plasmas, as well as laboratory plasma experiments, for plasma physicists to explore. I will review some of these topics, in particular magnetic reconnection, the rearrangement of the magnetic ?field topology of plasmas, which energizes many processes in nature and has been shown to also be critical in the nonlinear dynamics of many processes in toroidal fusion plasmas. Using global simulations, I will demonstrate the instrumental role of magnetic reconnection, which enables an innovative technique for producing current in fusion plasmas.

  114. Joint ATLAS/HET lunch discussion

    "Post LHC theory"

    Presented by Eder Izaguirre / Alessandro Tricoli, BNL

    Friday, April 13, 2018, 12:15 pm
    Building 510, Room 2-84

    Hosted by: Christoph Lehner

  115. Particle Physics Seminar

    "First Results from CUORE - Search for Neutrinoless Double Beta Decay in 130Te"

    Presented by Karsten Heeger, Yale University, Wright Laboratory

    Thursday, April 12, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale cryogenic experiment at Gran Sasso National Laboratory designed to search for neutrinoless double-beta decay (0νββ) in tellurium-130. The experiment consists of 988 ultracold tellurium dioxide bolometric crystals, which act as both the double-beta decay sources and detectors. An observation of neutrinoless double-beta decay would be direct evidence of lepton number violation and unambiguously prove that neutrinos are Majorana particles. This talk presents the first results from CUORE based on an exposure of 83.6 kg yr of tellurium dioxide. With this data we find no evidence for neutrinoless double-beta decay and set the world-leading limit on the rate of 0νββ in 130Te

  116. Physics Colloquium

    "Quantum Chromodynamics in the Exascale Era with the Emergence of Quantum Computing"

    Presented by Martin Savage, University of Washington

    Tuesday, April 10, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    A century of coherent experimental and theoretical investigations uncovered the laws of nature that underly nuclear physics ? Quantum Chromodynamics (QCD) and the electroweak interactions. While analytic techniques of quantum field theory have played a key role in understanding the dynamics of matter in high energy processes, they become inapplicable to low-energy nuclear structure and reactions, and dense systems. Expected increases in computational resources into the exascale era will enable Lattice QCD calculations to determine a range of important strong interaction processes directly from QCD. However, important finite density systems, non equilibrium systems, and inelastic processes are expected to remain a challenge for conventional computation. In this presentation, I will discuss the state-of-the-art Lattice QCD calculations, progress that is expected in the near future, and the potential of quantum computing to address Grand Challenge problems in nuclear physics.

  117. Nuclear Theory/RIKEN Seminar

    "Dense nuclear and quark matter from holography"

    Presented by Andreas Schmitt, University of Southampton

    Friday, April 6, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    QCD at large, but not asymptotically large, baryon density presents an enormous theoretical challenge because first-principle calculations are nearly impossible. Phenomenologically, dense QCD is of great interest for the interior of neutron stars, in particular after the recent detection of gravitational waves from neutron star mergers. I will discuss a holographic approach to dense matter, making use of the Sakai-Sugimoto model, which can account for both nuclear matter and quark matter and the transition between them. In particular, nucleons are implemented as instantons in the bulk, and I will discuss certain approximations for many-nucleon matter based on the flat-space instanton solution and present the resulting phase diagrams.

  118. HET Lunch Discussions

    "Isospin Breaking corrections in tau decays from Lattice QCD"

    Presented by Mattia Bruno, BNL

    Friday, April 6, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  119. Particle Physics Seminar

    "Time for High Luminosity – a new Detector for ATLAS"

    Presented by Joern Lange, Institut de Fisica d'Altes Energies (IFAE) Barcelona

    Thursday, April 5, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    To extend its physics reach, the Large Hadron Collider at CERN will be upgraded in 2024-2026 to deliver proton-proton collisions at 5-10 times higher luminosities than designed (HL-LHC). This will be a challenge for the ATLAS experiment that has to cope with higher particle densities, radiation and event pile-up of up to 200 interactions per bunch crossing. Apart from the planned exchange of the full inner tracker, a complete new detector is being proposed and developed to complement precise tracking with ultra-fast timing: the High Granularity Timing Detector (HGTD). It will exploit the fact that the primary vertices where the individual interactions take place are not only distributed in space, but also in time. Hence, measuring the time of each particle with about 30 ps precision allows to further suppress backgrounds from pile-up and restore the reconstruction performance of b-tagging, jets, isolated leptons and missing transverse energies, which is crucial for many physics analyses. The HGTD will cover a pseudo-rapidity range of 2.4 to 4.0 with a granularity of 1.3x1.3 mm2. It is only made possible by the rapid advance of a new silicon detector technology, namely Low Gain Avalanche Detectors (LGAD), which have been developed by CNM Barcelona and the CERN RD50 Collaboration and are now also produced by Hamamatsu, FBK, BNL and Micron. It has been shown that LGADs can fulfill the challenging HGTD requirements, especially also after the high radiation fluence levels expected at the end of life time of up to 5e15 neq/cm2. This presentation will motivate and introduce the HGTD and present the new LGAD sensor technology including performance measurements before and after irradiation. New developments such as 4D-tracking and possible other applications inside and outside High Energy Physics (forward detectors like AFP, low-energy X-rays, radio-therapy) will be discussed as well.

  120. Condensed-Matter Physics & Materials Science Seminar

    "Plastic Deformation at the Nanoscale and Superconductivity Enhancement in Decompression"

    Presented by Bin Chen, Shanghai Laboratory of Center for High Pressure Science & Technology Advanced Research (HPSTAR), China

    Thursday, April 5, 2018, 1:30 pm
    ISB Bldg. 734 Seminar Room 201 (upstairs)

    Hosted by: Cedomir Petrovic

    Plastic Deformation at the Nanoscale: Understanding the plastic deformation of nanocrystalline materials is a longstanding challenge [1,2]. Various controversial observations, mainly on the existence of dislocations and the mechanisms for a reversed Hall–Petch effect, have been reported. However, in situ observation of plastic deformation in ultrafine (sub-10 nm) nanocrystals has long been difficult, precluding the direct exploration of mechanics at the nanometer scale. By using a radial diamond-anvil cell (rDAC) x-ray diffraction technique we plastically deformed nickel to pressures above 35 GPa and observed that 1) dislocation-mediated deformation was still operative in as small as 3 nm nickel particles [3]; 2) 70 nm nickel particles were found to rotate more than any other grain size, signaling the reversal in the size dependence of grain rotation [4,5]; 3). Hall-Petch effect in nickel can be extended to 3 nm [6]. These observations demand considering the role of defects in the physical behaviors of nanomaterials. Superconductivity Enhancement in Decompression: An unexpected superconductivity enhancement was recently observed in decompressed In2Se3 [7]. The onset of superconductivity in In2Se3 occurred at 41.3 GPa with a critical temperature (Tc) of 3.7 K, peaking at 47.1 GPa. The striking observation shows that this layered chalcogenide remains superconducting during decompression down to 10.7 GPa. More surprisingly, the highest Tc in decompression was 8.2 K, a twofold increase in the same crystal structure as in compression. The novel decompression-induced superconductivity enhancement implies that it is possible to maintain pressure-induced superconductivity at lower or even ambient pressures with better superconducting performance. References: [1] B. Chen, et al., MRS Bulletin 41, 473 (2016). [2] H. K. Mao, et al., Matter and Radiation at Extremes, 1, 59 (2016). [3] B. Chen, et al., Science 338, 1448 (2012). [4] B. Chen, et al., Proc. Natl. Ac

  121. RIKEN Lunch Seminar

    "QCD crossover at zero and non-zero baryon densities"

    Presented by Patrick Steinbrecher, BNL

    Thursday, April 5, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  122. HET Seminar

    "Excluding a thin dark matter disk in the Milky Way with Gaia DR1"

    Presented by Katelin Schutz, UC Berkeley

    Thursday, April 5, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

    If a component of the dark matter has dissipative interactions, it could collapse to form a thin dark disk in our Galaxy coincident with the baryonic disk. It has been suggested that dark disks could explain a variety of observed phenomena, including mass extinction events due to periodic comet impacts. Using the first data release from the Gaia space observatory, I will present the results of a search for a dark disk via its effect on stellar kinematics in the Milky Way. I will discuss our strong new limits that disfavor the presence of a thin dark matter disk and present updated measurements on the total matter density in the solar neighborhood.

  123. HET Seminar has been CANCELLED for today

    "Excluding a thin dark matter disk in the Milky Way with Gaia DR1"

    Presented by Katelin Schutz, UC Berkeley

    Wednesday, April 4, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

    If a component of the dark matter has dissipative interactions, it could collapse to form a thin dark disk in our Galaxy coincident with the baryonic disk. It has been suggested that dark disks could explain a variety of observed phenomena, including mass extinction events due to periodic comet impacts. Using the first data release from the Gaia space observatory, I will present the results of a search for a dark disk via its effect on stellar kinematics in the Milky Way. I will discuss our strong new limits that disfavor the presence of a thin dark matter disk and present updated measurements on the total matter density in the solar neighborhood.

  124. Physics Colloquium

    "Eigenstate thermalization and its implications to statistical mechanics"

    Presented by Anatoli Polkovnikov, Boston University

    Tuesday, April 3, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    In this talk I will overview recent developments in understanding quantum chaos through random matrix theory. I will discuss various conjectures on the nature of quantum stationary states in chaotic systems and show numerical evidence supporting them. It is the random nature of eigenstates, which ultimately leads to loss of information about initial conditions and leads to emergence of statistical mechanics in isolated systems. I will then introduce the so-called Eigenstate Thermalization Hypothesis (ETH) ansatz first proposed by J. Deutsch and M. Srednicki in 90th, which gives a unified framework for the structure of physical observable in quantum chaotic systems. I will demonstrate how the ETH ansatz naturally leads to emergence of various thermodynamic relations. At the end of the talk I will mention some open problems.

  125. HET Lunch Discussions

    "Lattice QCD Study of Exclusive Channels in the Muon HVP"

    Presented by Aaron Meyer, BNL

    Friday, March 30, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  126. Particle Physics Seminar

    "Searches for squarks and gluinos with the ATLAS detector"

    Presented by Vakhtang Tsiskaridze, Stony Brook

    Thursday, March 29, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

  127. Condensed-Matter Physics & Materials Science Seminar

    "Non-abelian symmetries and applications in tensor networks"

    Presented by Andreas Weichselbaum, Brookhaven National Lab

    Thursday, March 29, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Igor Zaliznyak

    I will give a brief introduction to tensor network states with focus on exploiting all symmetries, abelian and non-abelian alike. I will briefly motivate a generic framework for finite-dimensional Lie algebras, which has been fully implemented in the tensor library QSpace [1]. The latter was already put under extensive scrutiny over the past couple of years. Along it already also gave rise to a range of excellent applications. Here, in particular, I will briefly highlight 1D density matrix renormalization group (DMRG) calculations on SU(N) Heisenberg ladders, 2D projected entangled pair state (PEPS) simulations on Spin-1 Kagome [2], and infinite-dimensional dynamical mean-field theory (DMFT) simulations on Hund's metals [3]. [1] A. Weichselbaum, Annals of Physics 327, 2972 (2012) [2] Liu et al., PRB 91 (R), 060403(R) (2015) [3] Stadler et al. PRL 115, 136401 (2015)

  128. Condensed-Matter Physics & Materials Science Seminar

    "Accurate spectral calculations for testing electronic structures, low energy excitations, and vibronic interactions"

    Presented by Keith Gilmore, The European Synchrotron Radiation Facility, France

    Thursday, March 29, 2018, 11 am
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Robert Konik

    Resonant inelastic x-ray scattering (RIXS) is a relatively new technique for probing low energy excitations in materials. In addition to traditional techniques, such as angle resolved photoemission, it has become an important, high precision characterization tool of strongly correlated electron materials. To calculate RIXS, and related core and valence level spectra, we solve the Bethe-Salpeter equation (BSE) based on a self-energy corrected density functional theory electronic structure. I outline our implementation of the BSE and use SrVO3 for demonstration. The sensitivity of spectral features to the self-energy approximation – whether G0W0, qpscGW, or DMFT – is highlighted. To include interactions beyond the usual BSE I introduce the cumulant expansion. Spectral functions derived from a GW self-energy are typically inadequate when the dressed Green's function is built via the Dyson equation. With the same GW self-energy, a superior Green's function and spectral function, implicitly including vertex corrections, is obtained through the cumulant expansion. I consider application of the GW-cumulant expansion to photoemission, photoabsorption, and X-ray scattering. Lastly, vibronic coupling has important impacts on these spectra. I show how to calculation the phonon contribution to photoemission, absorption and scattering with a vibronic cumulant.

  129. PubSci

    "PubSci: Nuclear Medicine for Personalized Cancer Treatment"

    Tuesday, March 27, 2018, 7 pm
    Napper Tandy's 60 E. Main Street Bay Shore, N

  130. Physics Colloquium

    "Particles Colliders: Past, Present and Future"

    Presented by Dmitri Denisov, Fermilab

    Tuesday, March 27, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    Developments of the particle colliders over last 50 years have seen tremendous progress in both the energy of the collisions and the intensity of the colliding beams. In order to reach even higher collision energy many fundamental inventions in the colliders design have been achieved. Progress to even higher energies was strongly stimulated by physics interests in studying smaller and smaller distances and in creation of heavier and heavier elementary particles. Experiments at colliders required major breakthroughs in the particle detection methods in order to discover new particles such as c and t quarks, gluons, tau lepton, W, Z and Higgs bosons which completed currently expected set of elementary particles. Options for even higher energy colliders will be discussed, including their design parameters, acceleration principles as well as construction challenges. Such colliders is the only way to understand the Nature at even smaller distances and create particles with higher masses than we can reach today.

  131. HET Lunch Discussion /Neutrino Discovery Initative

    "Boosted Dark Matter at DUNE"

    Presented by Lina Necib, Caltech

    Friday, March 23, 2018, 12:15 pm
    Building 510, Room - 2-160

  132. HET Seminar

    "Empirical Determination of Dark Matter Velocities"

    Presented by Lina Necib, Caltech

    Friday, March 23, 2018, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

  133. HET Seminar

    "Empirical Determination of Dark Matter Velocities"

    Presented by Lina Necib, Caltech

    Wednesday, March 21, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

  134. Physics Colloquium

    "Nuclear lattice simulations"

    Presented by Dean Lee, Michigan State University

    Tuesday, March 20, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    This is an introduction to how atomic nuclei and other quantum few- and many-body systems can be studied using lattice simulations. The first part of the talk explains the basic formalism called lattice effective field theory. The rest of the talk is a discussion of novel methods and the new physics insights one gains with each. The methods discussed are the adiabatic projection method for scattering and reaction calculations, pinhole algorithm for probing structure and thermodynamic properties, and eigenvector continuation for extending calculations to regions of parameter space where things otherwise break down.

  135. Condensed-Matter Physics & Materials Science Seminar

    "Spatial Resolution of Low-Loss EELS"

    Presented by R.F. Egerton, University of Alberta, Canada

    Tuesday, March 20, 2018, 2 pm
    Building 480 Conference Room

    Hosted by: Yimei Zhu

    Recent-generation TEM/STEM instruments fitted with an electron monochromator provide an energy resolution down to 0.01 eV for electron energy-loss spectroscopy (EELS) and are themselves capable of achieving a spatial resolution approaching 0.1 nm. Besides offering the possibility of vibrational-mode EELS for examining chemical bonds, these instruments could be useful for mapping the electronic properties (e.g. band gap) of insulators and semiconductors. However, basic physics imposes a spatial resolution of few nm (or tens of nm) for energy loss below 10 eV, due to delocalization of the inelastic scattering. We will discuss what might be done to improve the spatial resolution, to make low-loss EELS competitive with other techniques.

  136. Nuclear Physics Seminar

    "Probing the collectivity of heavy quarks in pPb collisions with prompt D0 elliptic flow using CMS detector"

    Presented by Zhenyu Chen, Rice University

    Tuesday, March 20, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Lijuan Ruan

    Recent years, evidence for collective effects has been revealed in pp and pPb collisions when looking at events releasing large number of particles. The experimental observations lead to a debate of the formation of strongly coupled Quark-Gluon Plasma in those small collision systems. Azimuthal anisotropy coefficient (vn) of heavy-flavor particles, and especially the comparison to light flavor particles vn, can shed light on the strength of the coupling between heavy flavor quarks and the hypothesized hydrodynamic medium at a significantly reduces size, and impose further constrains on different interpretations related to the origin of the observed collectivity. In this talk, the most recent results of prompt D0 meson elliptic flow (v2) in high-multiplicity pPb collisions are presented over a wide transverse momentum range. The results are compared to those of strange hadrons, including Kshort, Lambda, Cascade and Omega particles.

  137. Nuclear Theory/RIKEN Seminar

    "Correlators of twist-2 light-ray operators in the BFKL approximation"

    Presented by Ian Balitsky

    Friday, March 16, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Andrey Tarasov

    It is well known that BFKL gives anomalous dimensions of twist-2 operators of spin j in the "BFKL limit'' $g^2\righarrow 0,\omega\equiv j-1\righarrow 0,{g^2\over\omega}$ fixed. I demonstrate that such limit describes the non-local light-ray operators and present the results of calculation of two- and three-point correlation functions of these operators in this limit. The calculation is performed in ${\cal N}$=4 SYM but the result is valid in other gauge theories such as QCD.

  138. Condensed-Matter Physics & Materials Science Seminar

    "Quantum dimer models for high temperature superconductors"

    Presented by Garry Goldstein, Cambridge University, United Kingdom

    Friday, March 16, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Robert Konik

    In this talk we review the slave boson meanfield formulation of the fermion+boson quantum dimer model for the pseudogap phase of the high temperature superconductors. We show that in the presence of weak slowly varying external magnetic and electric fields the fermionic dimers undergo semiclassical motion in the external field. As a result in the presence of magnetic fields strong enough to destroy superconductivity the dimers undergo quantum oscillations. Indeed they satisfy Onsager quantization for their orbits and Lifshtiz-Kosevich formula for the amplitude of oscillations. We also compute the effective charges of the dimers in the presence of external magnetic fields as a function of temperature. We show that the effective magnetic charge changes sign from negative −e at low temperature to positive +e at high temperature. This leads to a change of the sign of the Hall coeÿcient as a function of temperature. We also compute the magnetoresistance as a function of the external field and temperature within a linearized Boltzmann equation approximation for the fermionic dimers. Furthermore we further show that the dimers undergo a Lifshitz transition as a function of doping with a van Hove singularity appearing at the Fermi surface near optimal doping ∼ 20%. Indeed the van Hove singularity leads to a divergence of the density of states and as such an optimum Tc. We study the interplay of nematic fluctuations and the van Hove singularity both of which occur near optimal doping. We show that the van Hove singularity modifies the critical properties of the QCP (quantum critical point) for nematic fluctuations and that the QCP may be described by Hertz Millis like theory with z = 4. This allows us to calculate the critical exponents of the nematic fluctuations and to show that the fermionic dimers have non-Fermi liquid behavior near the QCP with the self energy diverging ∼ |ω3/4| near the QCP.

  139. HET Lunch Discussions

    "Updated Global SMEFT Fit to Higgs, Diboson and Electroweak Data"

    Presented by Christopher Murphy, BNL

    Friday, March 16, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  140. Particle Physics Seminar

    "Precision Measurements of Asymmetries and Spectra in Neutron Decay"

    Presented by Brad Plaster, University of Kentucky

    Thursday, March 15, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    Precision measurements of various asymmetries in neutron decay permit an extraction of the weak axial-vector coupling constant, gA, a fundamental quantity important for weak-interaction physics and as a benchmark for lattice QCD calculations. I will discuss a recent new result from the UCNA Experiment at Los Alamos National Laboratory for a 0.16% precision result on gA from a measurement of the 'A' asymmetry, which represents the parity-violating angular correlation between the neutron's spin and the decay electron's momentum. This long-standing effort was carried out with a superconducting solenoidal electron spectrometer at the LANL Ultracold Neutron (UCN) facility. This new result will be placed in the context of historical results for gA and recent discrepant values for the neutron lifetime obtained via different experimental techniques. I will also discuss the first-ever extraction of the Fierz interference term 'b' in free neutron decay from an analysis of the electron's spectral shape as measured in the UCNA Experiment. A non-zero 'b' term would result from beyond-Standard Model interactions, such as Scalar or Tensor physics. Although the result for 'b' from the UCNA Experiment was systematics limited, it points to the requisite significant improvements in the characterization of the detector energy response that future experiments aimed at a measurement of 'b' will need to achieve in order to probe beyond Standard Model physics at a competitive precision.

  141. Condensed-Matter Physics & Materials Science Seminar

    "Splitting of electrons and violation of the Luttinger sum rule"

    Presented by Eoin Quinn, University of Amsterdam, Netherlands

    Thursday, March 15, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Robert Konik

    We obtain a controlled description of a strongly correlated regime of electronic behaviour. We argue that there are two ways to characterise the electronic degree of freedom, either by the canonical fermion algebra or by the graded Lie algebra su(2|2). The first underlies the Fermi liquid description of correlated matter, and we identify a novel regime governed by the latter. We obtain the electronic spectral function within a controlled approximation, and find a splitting in two of the electronic band. The Luttinger sum rule is violated and a Mott metal-insulator transition is exhibited.

  142. RIKEN Lunch Seminar

    "Hadronic light-by-light scattering in the muon g-2"

    Presented by Andreas Nyffeler, University of Mainz

    Thursday, March 15, 2018, 12:30 pm
    Building 510, Room 2-160

  143. Condensed-Matter Physics & Materials Science Seminar

    "Enabling emergent spin-orbit magnetism in iridate-based heterostructures"

    Presented by Jian Liu, The University of Tennessee, Knoxville

    Thursday, March 15, 2018, 11 am
    ISB Bldg. 734 Seminar Room 201 (upstairs)

    Hosted by: Mark Dean

    5d transition metal oxides have emerged as a novel playground for some of the most outstanding and challenging problems in condensed matter physics, such as metal-insulator transition and quantum magnetism. In particular, layered iridates hosting square lattices of IrO6 octahedra have drawn significant interests due to the electronic and magnetic analogy with high-Tc cuprates. However, materials of this kind are limited to a few Ruddlesden-Popper (RP) compounds. In this talk, I will discuss our recent work on overcoming this bottleneck by constructing such two-dimensional (2D) structures confined in superlattices grown by heteroepitaxy. By leveraging the layering control of epitaxial growth, we are not only able to develop new structural variants of layered iridates, but also unravel and exploit the intriguing spin-orbit-driven 2D magnetism beyond the cuprate physics yet invisible in the RP iridates. The results demonstrate the power of this approach in tailing the exchange interactions, enabling new magnetic controls, and providing unique insights into the emergent phenomena of 5d electrons.

  144. Center for Functional Nanomaterials Seminar

    "Metal oxide/semiconductor heterojunctions as carrier-selective contacts for photovoltaic applications"

    Presented by Gabriel Man

    Wednesday, March 14, 2018, 2 am
    CFN, Bldg. 735 - first, floor, conference room A

    Hosted by: Mingzhao Liu

    Solar radiation is a vast, distributed, and renewable energy source which Humanity can utilize via the photovoltaic effect. The goal of photovoltaic technology is to minimize the true costs, while maximizing the power conversion efficiency and lifetime of the cell/module. Interface-related approaches to achieving this goal are explored here, for two technologically-important classes of light absorbers: crystalline-silicon (c-Si) and metal halide perovskite (MHP). The simplest solar cell consists of a light absorber, sandwiched between two metals with dissimilar work functions. Carrier-selective contacts (CSC's), which are ubiquitous in modern solar cells, are added to improve the electrical performance. Solar cells require asymmetric carrier transport within the cell, which can be effected via electrostatic and/or effective fields, and CSC's augment the asymmetry by selectively transporting holes to one contact, and electrons to the other contact. The proper design and implementation of a CSC is crucial, as the performance, lifetime, and/or cost reduction of a solar cell can be hampered by a single interface or layer. A framework, consisting of eight core requirements, was developed from first-principles to evaluate the effectiveness of a given CSC. The framework includes some requirements which are well-recognized, such as the need for appropriate band offsets, and some requirements which are not well-recognized at the moment, such as the need for effective valence/conduction band density of states matching between the absorber and CSC. The application of the framework to multiple silicon-based and MHP-based CSC's revealed the difficulties of effectively designing and implementing a CSC. Three metal oxide/c-Si heterojunctions initially expected to yield comparable electron-selective contacts (ESC's), titanium dioxide/c-Si (TiO2/c-Si), zinc oxide/c-Si (ZnO/c-Si), and tin dioxide/c-Si (SnO2/c-Si), were instead discovered to be widely diff

  145. Particle Physics Seminar

    "From first beam to particle physics discoveries with petabytes of data"

    Presented by Paul Laycock, CERN

    Monday, March 12, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    The LHC experiments require huge, ever-increasing volumes of data to explore the frontiers of particle physics, and the grid provides the infrastructure to meet this challenge. Today, even medium sized experiments produce petabytes of data that need to be analysed by international collaborations and the relationship between particle physicists and their data has had to evolve to keep pace. Calibrating and systematically understanding detectors requires detailed information, deep learning algorithms promise to allow us to fully exploit our experiments, and on the other hand we want to analyse our data quickly and be the first to publish. This talk will first describe how, shortly after the Higgs discovery, ATLAS realised that the way that analysis was done had to change, and will briefly illustrate what those changes entailed. Next, the NA62 experiment will be described. Recording a billion events per day, NA62 aims to measure the very rare decay of a charged kaon to a charged pion and two neutrinos. The collaboration had to quickly implement petabyte scale data processing infrastructure to perform the sub-nanosecond calibrations needed to challenge the 10% precision of the theory prediction.

  146. Nuclear Theory/RIKEN Seminar

    "Yang-Mills action on the light front: MHV amplitudes and Wilson lines"

    Presented by Anna Stasto, Penn State

    Friday, March 9, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    The MHV action is the Yang-Mills action quantized on the light-front, where the two explicit physical gluonic degrees of freedom have been canonically transformed to a new set of fields. This transformation leads to the action with vertices being off-shell continuations of the MHV amplitudes. We show that the solution to the field transformation expressing one of the new fields in terms of the Yang-Mills field is a certain type of the Wilson line. More precisely, it is a straight infinite gauge link with a slope extending to the light-cone minus and the transverse direction. One of the consequences of that fact is that certain MHV vertices reduced partially on-shell are gauge invariant — a fact discovered before using conventional light-front perturbation theory. We also analyze the diagrammatic content of the field transformations leading to the MHV action. We found that the diagrams for the solution to the transformation (given by the Wilson line) and its inverse differ only by light-front energy denominators.

  147. HET Lunch Discussions

    "An update on the HVP contribution to the muon g-2"

    Presented by Christoph Lehner

    Friday, March 9, 2018, 12:15 pm
    Building 510, Room 2-160

  148. Particle Physics Seminar

    "New neutrino oscillation results from NOvA"

    Presented by Jeremy Wolcott, Tufts University

    Thursday, March 8, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    The NOvA experiment is an off-axis long-baseline neutrino oscillation experiment using the NuMI $\nu_{\mu}$ beam originating at Fermilab. By examining the disappearance of muon neutrinos and the appearance of electron neutrinos between the near detector at Fermilab and the far detector in Ash River, MN, NOvA has the potential to help answer a number of fundamental questions: Are the neutrinos' masses ordered the same way as those of the charged leptons? Do leptons experience charge-parity violation? Are there underlying symmetries in the way the neutrino states mix with one another? In this talk I will present NOvA's most recent constraints on the answers to those questions utilizing muon neutrino disappearance and electron neutrino appearance. These updated results are based on a 50% increase in exposure relative to previous results as well as numerous simulation and analysis improvements.

  149. HET Seminar

    "Dispersion relation for hadronic light-by-light scattering"

    Presented by Peter Stoffer, UC San Diego

    Wednesday, March 7, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

  150. Physics Colloquium

    "Quantum simulation of gauge theories in optical lattices"

    Presented by Alexei Bazavov, Michigan State University

    Tuesday, March 6, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    hile non-perturbative approaches such as lattice gauge theory led to significant advances in understanding the physics of strong interactions, many problems remain out of reach for classical computation, in particular, real-time dynamics or properties of QCD at finite baryon density that are being explored in heavy-ion collision experiments. Recent advances in the technology of engineering custom interactions for ultra-cold atomic gases in optical lattices opened a possibility for quantum simulations as was envisioned by R. Feynman in the 1980s. The main idea is that the degrees of freedom of the original system are mapped onto a quantum Hamiltonian whose dynamics can be realized in a laboratory. Many condensed matter Hamiltonians, such as Bose-Hubbard model, have been recently studied in this way. Quantum simulation of gauge theories is however challenging since the gauge symmetry is not naturally present in the ultra-cold atomic systems. I will review the current status of theoretical proposals for quantum simulation of field theories and then focus on our recent work on an explicitly gauge-invariant formulation of the Abelian-Higgs model for simulation on optical lattices.

  151. Instrumentation Division Seminar

    "Table-top MeV laser particle accelerator @ kHz repetition rate"

    Presented by Enam Chowdhury, Department of Physics, Ohio State University

    Tuesday, March 6, 2018, 2:30 pm
    Large Conference Room, Bldg. 535

    At the Extreme Light Lab at the Air Force Research Laboratory, Dayton, we explore light matter interaction at relativistic fields with liquid targets. Although demonstrations of up to 4 GeV1 electrons and ~100 MeV protons2 have been achieved in the past, all of these are not feasible as future accelerators, due to their slow duty cycle (usually single shot, rarely 1 Hz). There are many challenges to increasing the duty cycle, where laser technology, target technology, damage to system, target alignment, high repetition rate sub-micron plasma diagnostics provides nearly insurmountable obstacles. In this program, we developed ways to accelerate MeV x-rays, electrons3 and ions4 at kHz repetition rate with a small milli-joule class laser system, by developing a combination of suitable laser system, diagnostic system, target system and experimental data collection system capable of handling the high duty cycle. We also perform femtosecond-time resolution pump-probe imaging of the interaction, and extensive large scale relativistic laser plasma interaction simulations5 that reveal the nature of the acceleration processes. Such a system opens the door to extensive future application as a source for materials processing, radiation hardness testing, medical isotope production, time resolved proton probing on relativistic interactions, and many others.

  152. Nuclear Physics Seminar

    "Looking ahead to BESII: new observables and new theoretical frameworks"

    Presented by Yin Yi, MIT

    Tuesday, March 6, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Jia Jiangyong

    Upcoming beam energy scan (BES) phase II will explore the QCD phase diagram with an unprecedented precision and would potentially discover the QCD critical point. I will discuss recent theoretical developments aim at maximizing the discovery potential of BESII from both phenomenological and formal perspectives. First, I will discuss new observables which are very sensitive to the presence of the QCD critical point and are possible due to the iTPC upgrade. In the second part, I will report recent progress on understanding and describing hydrodynamic fluctuations. Remarkably, effects of hydrodynamic fluctuations can be potentially important for precise determination of shear viscosity at top RHIC energy and would play a crucial role near the QCD critical point.

  153. Nuclear Theory/RIKEN Seminar

    "Quark / Antiquark Correlations in Heavy-Light Ion Collisions"

    Presented by Matt Sievert, LANL

    Friday, March 2, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    It has long been known that sub-nucleonic fluctuations of the energy density in the initial stages of heavy ion collisions play an important role in generating the observed distributions of particles and their flow. These energy density fluctuations are dominated by the radiation of small-x gluons which are populated to classically large occupation numbers in the wave functions of ultra-relativistic heavy ions. While these soft gluons dominate the initial conditions for the energy density, it is quark production which determines the initial conditions of other conserved charges, like flavor and baryon number. With the recent development of state-of-the art hydrodynamics codes tailored to the Beam Energy Scan which can propagate these conserved charges into the final state, it is timely and important to calculate the initial conditions of these conserved charges from first principles in QCD. In this talk, I will present new results for the spatial correlations among quarks and antiquarks produced at mid-rapidity by pair production from small-x gluons. This single-pair production mechanism, which has been studied for some time in momentum space, is the leading contribution to these correlations in coordinate space for dilute-dense collisions. As one moves from the dilute-dense regime toward the dense-dense regime, correlations due to double pair production become more important, and these correlations persist over larger length scales than the single-pair production mechanism. Over nonperturbative length scales, only the correlations from the overlap geometry remain. I will present explicit results for quark-antiquark correlations due to single pair production, and I will outline some preliminary results for the various double-pair production mechanisms. The ultimate goal of this work will be to construct a code which can initialize these conserved charges over all length scales in heavy-ion collisions.

  154. HET Lunch Discussions

    "Semileptonic decays using Oktay-Kronfeld heavy quarks on the HISQ lattice"

    Presented by Yong-Chull Jang, BNL

    Friday, March 2, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  155. Condensed-Matter Physics & Materials Science Seminar

    "3D non-Fermi liquid behavior from 1D critical local moments"

    Presented by Laura Classen, BNL

    Thursday, March 1, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Igor Zaliznyak

    We study the temperature dependence of the electrical resistivity in a system composed of critical spin chains interacting with three dimensional conduction electrons and driven to criticality via an external magnetic field. The relevant experimental system is Yb2Pt2Pb, a metal where itinerant electrons coexist with localized moments of Yb-ions which can be described in terms of effective S = 1/2 spins with dominantly one-dimensional exchange interaction. The spin subsystem becomes critical in a relatively weak magnetic field, where it behaves like a Luttinger liquid. We theoretically examine a Kondo lattice with different effective space dimensionalities of the two interacting sub-systems. We characterize the corresponding non-Fermi liquid behavior due to the "local criticality" from the spins by calculating the electronic relaxation rate and the dc resistivity and establish its quasi linear temperature dependence.

  156. Joint BNL/SBU HET Seminar

    "Searching for Light Dark Matter with Dirac Materials"

    Presented by Yonatan Kahn, Princeton University

    Wednesday, February 28, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

    Dark matter with mass below a GeV is invisible to standard WIMP searches. In this talk I will present two recent proposals for direct detection of keV-GeV mass dark matter, both utilizing Dirac materials, where low-energy electronic excitations have linear dispersion relations and obey the Dirac equation. Dark matter with mass in the MeV-GeV range can eject electrons from graphene sheets, which can act as both targets and detectors when employed in a field-effect transistor mode, allowing directional detection. Dark matter as light as a few keV can excite electrons to the conduction band of Dirac semimetals like ZrTe5, where the linear dispersion protects the in-medium mass of the mediator and provides superior reach to a light dark photon mediator compared to superconductors. I will discuss recent progress towards experimental realizations of these proposals.

  157. High-Energy Physics & RIKEN Theory Seminar

    "Preparing High Energy Physics Software for the Future - the Community White Paper"

    Presented by Dr. Benedikt Hegner, CERN, Switzerland

    Wednesday, February 28, 2018, 12 pm
    Seminar Room, Bldg. 725

    Hosted by: Eric Lancon

    Particle physics has an ambitious and broad experimental program for the coming decades. This program requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment into R&D of software to acquire, manage, process, and analyses the shear amounts of data to be recorded. In planning for the High Luminosity LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that their efforts complement each other. In this spirit, the High Energy Physics community has created a white paper (arXiv:1712.06982) to describe and define the R&D activities required in order to prepare for this software upgrade. This presentation describes the expected software and computing challenges, and the plans to address them that are laid out in the white paper.

  158. Physics Colloquium

    "The Multi-Messenger Picture of a Neutron Star Merger"

    Presented by Brian Metzger, Columbia University

    Tuesday, February 27, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    On August 17 the LIGO/Virgo gravitational wave observatories detected the first binary neutron star merger event (GW170817), a discovery followed by the most ambitious electromagnetic (EM) follow-up campaign ever conducted. A gamma-ray burst (GRB) of short duration and very low luminosity was discovered by the Fermi and INTEGRAL satellites within 2 seconds of the merger. Within 11 hours, a bright but rapidly-fading thermal optical counterpart was discovered in the galaxy NGC 4993 at a distance of only 40 Mpc. The properties of the optical transient match remarkably well predictions for kilonova emission powered by the radioactive decay of heavy nuclei synthesized in the expanding merger ejecta by the r-process. The rapid spectral evolution of the kilonova emission to near-infrared wavelengths demonstrates that a portion of the ejecta contains heavy lanthanide nuclei. Two weeks after the merger, rising non-thermal X-ray and radio emission were detected from the position of the optical transient, consistent with delayed synchrotron afterglow radiation from an initially off-axis relativistic jet with the properties consistent with those of (on-axis) cosmological short GRB. I will describe a unified scenario for the range of EM counterparts from GW170817 and their implications for the astrophysical origin of the r-process and the properties of neutron stars. I will preview the upcoming era of multi-messenger astronomy, once Advanced LIGO/Virgo reach design sensitivity and a neutron star merger is detected every few weeks.

  159. HET Lunch Seminar

    "Recent indications of LU...... violations: A possible shaking of HEP in the making"

    Presented by Amarjit Soni, BNL

    Friday, February 23, 2018, 12 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  160. RIKEN Lunch Seminar

    "Drell-Yan process beyond collinear approximation"

    Presented by Stebel Tomasz, BNL

    Thursday, February 22, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  161. Condensed-Matter Physics & Materials Science Seminar

    "Topological Spin Excitations in a Highly Interconnected 3D Spin Lattice"

    Presented by Yuan Li, International Center for Quantum Materials, Peking University, China

    Thursday, February 22, 2018, 11 am
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Mark Dean

    The recent discovery of topological semimetals, which possess distinct electron-band crossing with non-trivial topological characteristics, has stimulated intense research interest. By extending the notion of symmetry-protected band crossing into one of the simplest magnetic groups, namely by including the symmetry of time-reversal followed by space-inversion, we predict the existence of topological magnon-band crossing in three-dimensional (3D) collinear antiferromagnets. The crossing takes on the forms of Dirac points and nodal lines, in the presence and absence, respectively, of the conservation of the total spin along the ordered moments. In a concrete example of a Heisenberg spin model for a "spin-web" compound, we theoretically demonstrate the presence of Dirac magnons over a wide parameter range using linear spin-wave approximation, and obtain the corresponding topological surface states [1]. Inelastic neutron scattering experiments have been carried out to detect the bulk magnon-band crossing in a single-crystal sample. The highly interconnected nature of the spin lattice suppresses quantum fluctuations and facilitates our experimental observation, leading to remarkably clean experimental data and very good agreement with the linear spin-wave calculations. The predicted topological band crossing is confirmed [2]. [1] K. Li et al., PRL 119, 247202 (2017). [2] W. Yao et al., arXiv:1711.00632.

  162. HET Seminar

    "Analysis of a Dilaton EFT for Lattice Data"

    Presented by Thomas Appelquist, Yale University

    Wednesday, February 21, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christoph Murphy

  163. Particle Physics Seminar

    "21-cm cosmology topics"

    Presented by Dr. Francisco Villaescusa-Navarro, Center for Computational Astrophysics, Flatiron Institute

    Thursday, February 15, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chris Sheehy

  164. Physics Colloquium

    "The Social Life of Heavy Quarks"

    Presented by Marek Karliner, Tel Aviv University

    Tuesday, February 13, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    I will discuss recent developments regarding new types of hadrons involving heavy quarks: hadronic molecules, doubly heavy baryons, stable tetraquarks and others. I will also explain how the discovery of the doubly heavy baryon leads to quark-level analogue of nuclear fusion, with energy release per reaction an order of magnitude greater than in ordinary fusion.

  165. Condensed-Matter Physics & Materials Science Seminar

    "Nematic superconductivity in topological materials"

    Presented by Matt Smylie, Argonne National Laboratory

    Tuesday, February 13, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Genda Gu

    In a topological superconductor, a bulk superconducting gap induces a symmetry-protected gapless superconducting surface state. This surface state can host exotic Majorana zero modes, which are expected to revolutionize computation technology through energy-efficient fault-tolerant quantum computing. In this talk, we will discuss the search for bulk topological superconductors and the discovery of nematic superconductivity in MxBi2Se3 (M=Cu,Sr,Nb), where the superconducting system spontaneously breaks rotational symmetry at Tc. The nematic superconducting state and possible origins of the rotational symmetry breaking will be explored, with many conventional causes being eliminated.

  166. Computational Science Initiative Event

    "Physics Informed Machine Learning"

    Presented by Michael (Mischa) Chertkov, Los Alamos National Lab

    Tuesday, February 13, 2018, 10:30 am
    Seminar Room, Bldg. 725

    Hosted by: Frank Alexander

    Machine Learning (ML) capabilities are in a phase of tremendous growth, and there is great opportunity to point these tools toward physical modeling. The challenge is to incorporate domain expertise from traditional scientific discovery into next-generation ML models. We propose to develop new Physics Informed Machine Learning (PIML) algorithms that extend cutting-edge computational and algorithmic ML tools and merge them with physical knowledge in the form of constraints, symmetries, and domain expertise regarding effective degrees of freedom. This PIML methodology is illustrated on the following four enabling examples: 1. Topology and Parameter Estimation in Power Grids [based on arXiv:1710.10727] 2. Creating Turbulent Flows with Deep Learning [based on an APS/DFD2017 abstract] 3. Learning Graphical Models [Science 2018 in print; arXiv:1612.05024] 4. Renormalization of Tensor Networks (Graphical Models) [based on arXiv:1801.01649 and ICML2018 submission]

  167. Joint Nuclear Theory and HET Seminar

    "TeV Scale Lepton Number Violation: Neutrinoless Double Beta Decay & the LHC"

    Presented by Michael Ramsey-Musolf, U. Mass. Amherst

    Friday, February 9, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

  168. RIKEN Lunch Seminar

    "Biased nuclear gluon distribution from a reweighted JIMWLK small-x ensemble"

    Presented by Adrian Dumitru, Baruch College/BNL

    Thursday, February 8, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  169. Nuclear Theory/RIKEN Seminar

    "New nonperturbative scales and glueballs in confining gauge theories"

    Presented by Mohamed Anber, Lewis & Clark College

    Friday, February 2, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    Studying confining gauge theories on a circle can provide answers to some of the deepest questions about QCD. In this talk, I start by summarizing the main characteristics shared by the compactified theories and their four dimensional cousins. Next, I show that the glueball spectrum of the compactified theories is much richer than what have been thought before. In particular, new nonperturbative scales and glueballs emerge in the deep IR regime of the theory. I discuss the spectrum in the context of super Yang-Mills and show that the lightest glueball states fill a chiral supermultiplet with doubly nonperturbative binding energy. I end with possible implications of these findings for the four dimensional gauge theories.

  170. NSLS-II Friday Lunchtime Seminar Series

    "Combining high energy x-ray diffraction techniques with laser-induced fluorescence in operando catalysis"

    Presented by Uta Hejral, Lund University, Sweden

    Friday, February 2, 2018, 12 pm
    NSLS-II Bldg. 743 Rm 156

    Hosted by: M. Abeykoon, S. Chodankar, B. Ocko, T. Tanabe, J. Thieme

  171. RIKEN Lunch Seminar

    "The Coulomb Branch of N=4 SYM and Its Gravity dual as a New Holographic Model to QCD"

    Presented by Kiminad Mamo, Stony Brook

    Thursday, February 1, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

  172. Joint BNL / SBU Seminar

    "New SM Physics and the LHC"

    Presented by Yuval Grossman, Cornell University

    Wednesday, January 31, 2018, 2:30 pm
    Stony Brook University YITP

  173. Condensed-Matter Physics & Materials Science Seminar

    "Establishing Jeff =3/2 Ground State in a Lacunar Spinel GaTa4Se8"

    Presented by Myung Joon Han, Korea Advanced Institute of Science and Technology (KAIST)

    Wednesday, January 31, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Sangkook Choi

    In this talk, after briefly introducing the research activities in my group, I will present our recent progress on GaTa4Se8 which is known as a 'paramagnetic Mott' insulator and exhibits superconducting transition under pressure. Its low temperature behaviors found in susceptibility and specific heat measurement have not yet been clearly understood. The important first step to study these intriguing phenomena and the relationship between them is to clarify the nature of its electronic and magnetic property. By using first-principles band structure calculation and resonant inelastic x-ray scattering technique, we show that GaTa4Se8 is a novel 'Jeff=3/2 Mott' insulator in which spin-orbit interaction plays a key role to form a gap together with electronic correlation. The excitations involving the Jeff = 1/2 molecular orbital are absent only at the Ta L2 edge, manifesting the realization of the molecular Jeff = 3/2 ground state in GaTa4Se8. Based on this finding, the possible consequences of the Jeff = 3/2 state will be discussed

  174. Physics Colloquium

    "Fast Radio Bursts"

    Presented by Jeff Peterson, Carnegie Mellon University

    Tuesday, January 30, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    Fast Radio Bursts are millisecond flashes of radio emission that appear randomly across the sky. Since the first report of a burst in 2006, over 20 of these FRBs have been reported. I will review the evidence that FRB sources are at cosmological distances and therefore have inferred brightness temperatures as high as 10^35 K, twenty orders of magnitude higher than gamma ray bursts. The all-sky rate of these events is estimated to be about 5000 per day, so the new HIRAX telescope in South Africa will have the potential to detect 10 events per day. HIRAX will also localize the emission to a single galaxy, so there will be much more information on these mysterious objects in the next few years.

  175. Joint Nuclear and Particle Physics Seminar

    "The SNOLAB Science Programme: cutting-edge science from a deep hole in the ground"

    Presented by Nigel Smith, SNOLab

    Tuesday, January 30, 2018, 1:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Hong Ma

    SNOLAB is a deep underground research facility, hosted 2km beneath the surface of the Earth in a working mine at Creighton, near Sudbury, Ontario. Initially the site of the Sudbury Neutrino Observatory, which unambiguously demonstrated flavour-change in neutrinos created in the fusion process of the Sun, SNOLAB now hosts a multi-disciplinary programme. Why do we need to go to such great depths to probe the Universe? This work, and several of the major questions studied in contemporary astro-particle and sub-atomic physics, such as the search for the Galactic dark matter, and studies of neutrinos from supernova, require the ultra-quiet radiation environment afforded by deep underground facilities like SNOLAB. In these facilities, the cosmic-radiation induced backgrounds in the detection systems are reduced to a manageable level, with additional shielding from natural ambient radioactivity and low background construction of detector systems. This talk will provide a review of the science programme at SNOLAB outlining the main science objectives, will review the detectors used for these studies, and outline future plans for the facility.

  176. Particle Physics Seminar

    "A Tale of Two Higgs"

    Presented by Baojia Tong, Harvard University

    Thursday, January 25, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    An enhanced production of double Higgs bosons at the LHC would be a clear sign of beyond Standard Model physics. An ATLAS search is performed for resonant and non-resonant production, where the two Higgs bosons both decay to a pair of Bottom quarks. The analyses use up to ~13/36 fb−1 of p-p collision data collected at 13 TeV. The talk will focus on the boosted analysis, with the resolved analysis introduced as well. Other RunII double Higgs search results and future prospect will also be discussed.

  177. RIKEN Lunch Seminar

    "Exact results on massless 3-flavor QCD through new anomaly matching"

    Presented by Yuya Tanizaki, RBRC

    Thursday, January 25, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    Recently, we find a new 't Hooft anomaly of massless 3-flavor QCD, and it turns out to be useful for constraining the possible chiral symmetry breaking at finite density and zero temperature. We briefly review the anomaly matching by a toy example, and show that massless 3-flavor QCD has an 't Hooft anomaly related to ''center'' and discrete axial symmetries. We also discuss its consequences on the expectation value of the special symmetry-twisting operator, which gives the phase diagram of so-called Z(3)-QCD.

  178. Physics Colloquium

    "Cold Atom Sensing: Gravity, Tomography, and Gyroscopes"

    Presented by Steve Libby, LLNL

    Tuesday, January 23, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    The ability to use lasers to cool atoms to micro-kelvin temperatures and to subsequently control their quantum mechanical behavior1 has led to the development of exquisitely precise 'quantum' sensors.2 Applications of these sensors include the measurement of local gravitational anomalies to unprecedented accuracy and very accurate, highly stable gyroscopes. Our LLNL - AOSense, Inc. collaboration is pursuing diverse applications of these sensors that directly exploit their extraordinary scale factor stability, low noise and bias drift characteristics. These applications include shielded threat detection in passing vehicles, emergency response, and treaty verification, all of which require rapid, passive methods to determine hidden mass configurations precisely and/or verify the masses present in containers. Such dense, localized objects can in principle be discovered and accurately measured by their effect on the local gravitational field.3 Furthermore, near field measurements of these gravitational perturbations from multiple vantage points allow for a kind of gravitational 'tomography,' leading to the real-time determination of the hidden mass distribution. Additionally, we are interested in the potential of atom interferometer Sagnac gyroscopes to do accurate 'dead reckoning' navigation without the aid of GPS.4 After reviewing the physics of atom interferometry in atomic fountain-Mach-Zehnder and Sagnac configurations, I will describe the development of a 'gravity tomography' signal analysis system for vehicle portals, including the optimal synthesis of the gravitational sensor signals with complementary radiation detection.

  179. Nuclear Physics Seminar

    "Probing the Quark-Gluon Plasma with Open Heavy Flavor Mesons using CMS detector"

    Presented by Professor Yen-Jie Lee, MIT

    Tuesday, January 23, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Rongrong Ma

    The measurements of heavy flavor production and collective flow could be used to extract the properties of the high-density QCD medium created in heavy-ion collisions as heavy quarks are sensitive to the transport properties of the medium and may interact with the QCD matter differently from light quarks. In particular, the comparison between the nuclear modification factors (RAA) of light- and heavy-flavor particles provides insights into the expected flavor dependence of in-medium parton energy loss. Furthermore, azimuthal anisotropy coefficient (vn) of heavy-flavor particles provide information about the degree of the thermalization of the bulk medium at low pT, and unique information about the path length dependence of heavy quark energy loss at high pT. Recently, a comprehensive heavy flavor program is established in the CMS collaboration including the detection of charm and beauty meson. Using the large statistics heavy ion data samples collected during the 2015 and 2016 LHC runs, high precision open charm and beauty measurements are performed with CMS over a wide transverse momentum range. This allows us to set an important milestone in our understanding of the interactions between heavy quarks and the medium. In this talk, the most recent results of v2 and v3 of D0 mesons in PbPb collisions at 5.02 TeV are presented and compared to the same results for charged hadrons at the same energy. Latest results on nuclear modification factor of D, non-prompt J/psi and B mesons in PbPb collisions are also presented.

  180. Condensed-Matter Physics & Materials Science Seminar

    "Spin-orbit coupling and electronic correlations in Hund's metals: Sr2RuO4"

    Presented by Minjae Kim, École Polytechnique, France

    Monday, January 22, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Gabi Kotliar

    We investigate the interplay of spin-orbit coupling (SOC) and Hund's rule coupling driven electronic correlations in Sr2RuO4 using dynamical mean-field theory. We find that the orbital diagonal components of the dynamical electronic correlations are unaffected by the SOC, which validates the concept of a Hund's metal in the presence of SOC. In contrast, SOC itself is enhanced by approximately a factor of two by electronic correlations. We introduce the concept of an energy dependent quasiparticle SOC, which is found to be essential in accounting simultaneously for: (i) the Fermi surface (ii) the low-energy dispersion of quasiparticles and (iii) the splitting between bands at higher binding energy. Our calculations are in good agreement with available experimental data. References: [1-4] [1] C. Veenstra et al., Physical Review Letters 112, 127002 (2014) [2] M. Haverkort et al., Physical Review Letters 101, 026406 (2008) [3] J. Mravlje et al., Physical Review Letters 106, 096401 (2011) [4] M. Kim et al., arXiv preprint arXiv:1707.02462 (2017)

  181. Nuclear Theory/RIKEN Seminar

    "Semi-inclusive jet cross sections within SCET"

    Presented by Felix Ringer, LBL

    Friday, January 19, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    We review the de nition of semi-inclusive jet functions within Soft Collinear E ective Theory (SCET) and their application to inclusive jet cross sections. We consider the fully inclusive production cross section of jets as well as several jet substructure observables in proton-proton collisions relevant for the LHC and RHIC. The corresponding semi-inclusive jet functions satisfy renormalization group (RG) equations which take the form of standard timelike DGLAP evolution equations, analogous to collinear fragmentation functions. By solving these RG equations, the resummation of potentially large single logarithms n s lnn R can be achieved. We present numerical results at NLO+NLLR accuracy and compare to the available data.

  182. Particle Physics Seminar

    "Search for the Higgs boson produced in association with top quarks and decaying into a b quark pair with the ATLAS detector at LHC"

    Presented by Thomas Calvet, Stony Brook University

    Thursday, January 18, 2018, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    The discovery of a particle compatible with the Standard Model (SM) Higgs boson in 2012 by the ATLAS and CMS collaborations at LHC is a milestone in particle physics. In order to assess whether or not this Higgs boson belongs to the SM, it is necessary to measure its properties, in particular its coupling to the top quark (the strongest Yukawa coupling in the SM). The associated production of a Higgs boson with a pair of top quarks, ttH gives the most favorable direct access to the top quark Yukawa coupling and is accessible for the first time in LHC Run 2. A search for the ttH production with the Higgs boson decaying into a b quark pair, ttH(bb), will be presented. It uses the 36.1 fb^-1 of data recorded by the ATLAS detector in 2015 and 2016. The main limitation to the search of ttH(bb) events is the tt+jets background and its systematic uncertainties. To achieve sufficient sensitivity, this complex analysis relies on several advanced tools to separate the leading background tt+jets from the signal, and to extract both of these processes from data (multi-variate analysis, profile likelihood fit, etc.). All these key aspects of the analysis will be discussed. The combination of the ttH(bb) channel with the other decay modes is necessary to improve the sensitivity to the ttH production mode. This combination leads to 4.2 sigma evidence of the ttH production and will be also presented.

  183. RIKEN Lunch Seminar

    "World-line Approach to Chiral Kinetic Theory and the Chiral Magnetic Effect"

    Presented by Niklas Mueller, BNL

    Thursday, January 18, 2018, 12:30 pm
    Building 510, Room 1-224

    Hosted by: Enrico Rinaldi

    Experimental searches for messengers of CP- and P- odd phenomena at RHIC and LHC have attracted much interest and are a prime motivation for significant theoretical effort: Anomalous and topological effects receive important contributions from the pre-equilibrium phase of a collision and an interesting question of phenomenological relevance is how the chiral imbalance generated at early times persists through a fluctuating background of sphalerons in addition to other "non-anomalous" interactions with the QGP. To address this question, we construct a relativistic chiral kinetic theory using the world-line formulation of quantum field theory. We outline how Berry's phase arises in this framework, and how its effects can be clearly distinguished from those arising from the chiral anomaly. We further outline how this framework can be matched to classical statistical simulations at early times and to anomalous chiral hydrodynamics at late times.

  184. Environmental & Climate Sciences Department Seminar

    "Understanding the Structure and Dynamics of Long-Duration Floods using Physics Informed Bayesian Multilevel Models"

    Presented by Naresh Devineni, CUNY

    Thursday, January 18, 2018, 11 am
    Conference Room Bldg 815E

    Hosted by: Bob McGraw

    Long duration floods cause substantial damage and prolonged interruptions to water resource facilities, critical infrastructure, and regional economic development. We present a novel physics-based model for inference of such floods with a deeper understanding of dynamically integrated nexus of land surface wetness, effective atmospheric blocking/circulation, and moisture transport/release mechanism. Diagnostic results indicate that the flood duration is varying in proportion to the antecedent flow condition which itself is a function of the available moisture in the air, the persistency in atmospheric pressure blocking, convergence of water vapor, and the effectiveness of divergent wind to condense the aforesaid atmospheric water vapor into liquid precipitation. A physics-based Bayesian inference model is developed that considers the complex interactions between moisture transport, synoptic-to-large-scale atmospheric blocking/circulation pattern, and the antecedent wetness condition in the basin. We explain more than 80% variations in flood duration with a high success rate on the occurrence of long duration floods. Our findings underline that the synergy between a large persistent low-pressure blocking system and a higher rate of divergent wind often triggers a long duration flood, even in the presence of moderate moisture supply in the atmosphere. This condition in turn causes an extremely long duration flood if the basin-wide surface wetness prior to the flood event was already high.

  185. Condensed-Matter Physics & Materials Science Seminar

    ""In situ characterization of the phase behavior of metal oxides at extreme conditions""

    Presented by Leighanne Gallington, Argonne National Laboratory

    Wednesday, January 17, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Room 201 (upstairs)

    Hosted by: Ian Robinson

    In situ characterization of the phase behavior of materials in the lab is complicated by the difficulty of designing compatible sample environments as well as the long time scales required to acquire diffraction data with sufficient counting statistics for crystallographic analyses. The high energy x-rays available at synchrotron sources allow for penetration of most sample environments, while high flux allows for rapid acquisition of diffraction patterns, thereby allowing construction of detailed phase diagrams. Low and negative thermal expansion (NTE) materials have been studied extensively, as they can potentially be used to create composites with finely controlled thermal expansion characteristics, improved resistance to thermal shock, and a broader range of operating temperatures.1-4 While the thermal expansion behavior of the NTE materials ZrW2O8 and HfW2O8 was well-described at ambient pressures,4-6 knowledge of the effects of stress on their thermal expansion was limited.7 In situ synchrotron powder diffraction was utilized to explore the role of orientational disorder in determining both the phase behavior and the thermoelastic properties of these materials. An especially designed pressure cell allowed for simultaneous sampling of temperatures up to 513 K and pressures up to 414 MPa.8 Reversible compression-induced orientational disordering of MO4 tetrahedra occurred concomitantly with elastic softening on heating and enhanced negative thermal expansion upon compression in ZrW2O8 and HfW2O8, but only in the ordered phase.9, 10 In light of the comparatively recent nuclear disaster in Fukushima, understanding interactions and phase behavior in nuclear fuels under severe accident conditions is of paramount interest. While diffraction measurements have been performed on materials recovered from melts of corium (UO2-ZrO2), there is a lack of in situ characterization of this material at elevated temperatures. Achieving the extreme temperatures required

  186. Physics Colloquium

    "Nuclear nonproliferation: the role of Brookhaven, and the nuclear agreement with Iran"

    Presented by Susan Pepper & Leslie Fishbone, BNL

    Tuesday, January 16, 2018, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

  187. Particle Physics Seminar

    "Improved Point Source Detection in Crowded Fields using Probabilistic Cataloguing"

    Presented by Stephen Portillo, Harvard University

    Tuesday, January 16, 2018, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Erin Sheldon

    Cataloging is challenging in crowded fields because sources are extremely covariant with their neighbors and blending makes even the number of sources ambiguous. We present the first optical probabilistic stellar catalogue, cataloguing a crowded (~0.1 sources per pixel) SDSS r band image from M2. We show that our probabilistic catalogue goes more than a magnitude deeper than the DAOPHOT while having a lower false discovery rate brighter than 20th magnitude. We detail our efforts to speed up the method and extend it to galaxies, making probabilistic cataloguing applicable to the data that will be collected in the LSST era.

  188. HET Lunch Discussions

    "Precision physics in the LHC era"

    Presented by Pier Paolo Giardino, BNL

    Friday, January 12, 2018, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  189. Condensed-Matter Physics & Materials Science Seminar

    "Singular density fluctuations in the strange metal phase of Bi2Sr2CaCu2O8+x observed with momentum-resolved EELS (M-EELS)"

    Presented by Peter Abbamonte, University of Illinois at Urbana Champaign

    Friday, January 12, 2018, 11 am
    ISB Bldg. 734, Conf. Room 201 (upstairs)

    Hosted by: Peter D. Johnson

    High-temperature superconductivity arises out of an anomalous normal state commonly referred to as a "bad" or "strange" metal, since it lacks the usual signatures of electron quasiparticles. In ordinary metals, such quasiparticles manifest as propagating collective modes encoded in the dynamic charge susceptibility ??(q,?), which describes the response of the system to applied fields. However, the analogous collective modes of a strange metal are currently unknown. Here, we present the first measurement of ??(q,?) for a prototypical strange metal, Bi2.1Sr1.9CaCu2O8+x (BSCCO), using momentum-resolved inelastic electron scattering (M-EELS). We discover a surprising energy- and momentum-independent continuum of fluctuations extending up to 1 eV, at odds with the dispersive plasmons expected in normal metals. This spectrum is found to be temperature-independent across the superconducting phase transition at optimal doping. Tuning the composition to overdoping, where a crossover to Fermi liquid behavior is expected, this momentum-independent continuum is found to persist, though a 0.5 eV gap-like feature now emerges at low temperature. Our results indicate that the phenomenon underlying the strange metal is a singular form a charge dynamics of a new kind, that does not fit into any known picture of quantum critical scaling.

  190. Condensed-Matter Physics & Materials Science Seminar

    "Bose condensation of excitons in TiSe2"

    Presented by Peter Abbamonte, University of Illinois at Urbana–Champaign

    Thursday, January 11, 2018, 1:30 pm
    ISB Bldg. 734, Conf. Room 201 (upstairs)

    Hosted by: Peter D. Johnson

    Bose condensation has shaped our understanding of macroscopic quantum phenomena, having been realized in superconductors, atomic gases, and liquid helium. Excitons are bosons that have been predicted to condense into either a superfluid or an insulating electronic crystal. But definitive evidence for a thermodynamically stable exciton condensate has never been achieved. In this talk I will describe our use of momentum-resolved electron energy-loss spectroscopy (M-EELS) to study the valence plasmon in the transition metal dichalcogenide semimetal, 1T-TiSe2. Near the phase transition temperature, TC = 190 K, the plasmon energy falls to zero at nonzero momentum, indicating dynamical slowing down of plasma fluctuations and crystallization of the valence electrons into an exciton condensate. At low temperature, the plasmon evolves into an amplitude mode of this electronic crystal. Our study represents the first observation of a soft plasmon in any material, the first definitive evidence for exciton condensation in a three-dimensional solid, and the discovery of a new form of matter, "excitonium."

  191. RIKEN Lunch Seminar

    "Three-dimensional gauge theories using lattice regularization"

    Presented by Nikhil Karthik

    Thursday, January 11, 2018, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Yuya Tanizaki

    Three-dimensional gauge theories with massless fermions provide a simple yet non-perturbative setting to understand why QCD has a scale, and also provide effective descriptions of condensed matter systems. Along these lines, I will present results on infra-red scaling and scale-breaking in three-dimensional QED, QCD and large-Nc theories. I will also present some preliminary results on three-dimensional QED with one flavor of fermion regulated with and without parity anomaly.

  192. Condensed-Matter Physics & Materials Science Seminar

    ""Photoemission studies of the electronic properties of rare-earth intermetallics and oxide interface""

    Presented by Alla Chikina, Paul Scherrer Institute, Switzerland

    Monday, January 8, 2018, 3 pm
    ISB Bldg. 734 Seminar Room 201 (upstairs)

    Hosted by: Cedomir Petrovic

    Longer than 70 years solid state research has been focused on the study of materials with strong electron correlations due to their remarkable electronic and magnetic properties. In such systems, the average energy of the Coulomb interaction is greater or comparable to its kinetic energy and electrons tend to be localized. This localization is strong enough that electrons can be considered in the framework of the atomic approach. Interaction with itinerant electrons makes the interpretation of their physical properties more complicated. A typical example of a strongly-correlated system contains transition and rare earth (RE) elements. Here, I present both theoretical and experimental insight into the itinerant-localized electron interaction in rare-earth 122 silicides (RERh2Si2). The properties of RERh2Si2 change from the heavy-fermion behavior in YbRh2Si2 up to well-pronounced magnetic properties in EuRh2Si2 and GdRh2Si2. The competition between the Kondo effect and the magnetic RKKY interactions determines the properties of a large class of materials which have localized 4f magnetic moments coupled to itinerant valence electrons. The strong electron correlations, also well known in the transition metal oxides, rise up their remarkable functional and magnetic properties. It gives a route in a manipulation of electron, spin, orbital and lattice degrees of freedom for novel electronic and spintronic devices based on oxide interfaces. An important role in the electronic and magnetic properties of this interface is played by oxygen vacancies which form a dichotomic electron system where strongly correlated localized electrons in the in-gap states (IGSs) coexist with less correlated ones constituting the mobile two-dimensional electron system (2DES). On the example of the interface between LaAlO3 and SrTiO3 we consider a complex band ordering in the dichotomic LAO/STO electron system that goes beyond the conventional eg vs t2g picture.

  193. Nuclear Theory Seminar

    "Thermodynamics of string bits"

    Presented by Sourav Raha, University of Florida

    Monday, January 8, 2018, 11 am
    Large Seminar Room, Bldg. 510

    Hosted by: Andrey Tarasov

    We study the Hagedorn transition in the singlet sector of the simplest super-string bit model in the tensionless limit. The gauge group of our model is SU(N) and this transition takes place when N is infinite. We use orthogonality of group characters in order to calculate the partition function. At the Hagedorn temperature there is a change in the distribution of parameters that maximize this partition function. We conclude by devising a field-theoretic interpretation of the this phenomenon.

  194. Nuclear Theory/RIKEN Seminar

    "Thermodynamics of string bits"

    Presented by Sourav Raha, University of Florida

    Friday, January 5, 2018, 2 pm
    Small Seminar Room, Bldg. 510

    We study the Hagedorn transition in the singlet sector of the simplest super-string bit model in the tensionless limit. The gauge group of our model is SU(N) and this transition takes place when N is infinite. We use orthogonality of group characters in order to calculate the partition function. At the Hagedorn temperature there is a change in the distribution of parameters that maximize this partition function. We conclude by devising a field-theoretic interpretation of the this phenomenon.

  195. Condensed-Matter Physics & Materials Science Seminar

    "Illuminating rationally engineered complex oxides"

    Presented by Derek Meyers, BNL

    Friday, January 5, 2018, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Mark Dean

    Advances in unit cell scale synthesis have unlocked the ability to create artificial materials at the interface of complex oxides. This opens the door to the rational design of materials properties. To explore the spin, charge, and orbital character of these synthetic materials, resonant x-ray scattering techniques are utilized which unveil their long-range ordering and low energy excitations. In this talk, we will explore several recent examples of this new methodology and provide an outlook on the future of this emergent field.

  196. Condensed-Matter Physics & Materials Science Seminar

    "Spin fluctuations in 122 transition metal arsenides measured using inelastic neutron scattering technique"

    Presented by Aashish Sapkota, Ames Laboratory

    Thursday, December 21, 2017, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: John Tranquada

    122 transition metal compounds with ThCr2Si2-type structure have been extensively studied because of their wide range of interesting physical properties like superconductivity, valence fluctuations, various magnetic ground states, etc. A subset (ATM2Pn2) of this class consisting of alkaline earth metals (A), 3d transition metals (TM) and pnictogen (Pn) attracted significant interest after discovery of an unconventional superconductivity in 122 iron arsenide compounds. In 122 iron arsenide superconductors, magnetism is in close proximity to the superconductivity and the spin fluctuations are considered as a key component for the pairing mechanism for superconductivity. These properties as well as the wide range of magnetic ground states, found in ATM2As2, motivated a detail studies of the magnetism in these compounds and neutron scattering technique has been extensively used for the study. In this seminar, I will discuss our results of inelastic neutron scattering measurements of the spin fluctuations in two compounds [CaCo1.86As2 and Ca(Fe1-xCox)2As2] of ATM2Pn2 class. First, I will discuss extremely extended spin fluctuations along two directions of reciprocal space in CaCo1.86As2, which shows A-type antiferromagnetic ground states. The result suggests that CaCo1.86As2 is highly-frustrated and is a unique example of highly-frustrated square-lattice system. Next, I will discuss the evolution of the spin fluctuations in Co-doped CaFe2As2 and compare it to that of Co-doped BaFe2As2. In this part, I will also discuss a peculiar suppression of the spin fluctuations with temperature observed in Ca(Fe1-xCox)2As2, x = 0.030 compound, which shows superconducting ground state.

  197. Nuclear Theory/RIKEN Seminar

    "Simultaneous extraction of spin-dependent parton distributions"

    Presented by Nobuo Sato, Jlab/University of Connecticut

    Friday, December 15, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Andrey Tarasov

    In this talk, I will present a recent global QCD analysis of spin-dependent PDFs and FFs using a MC methodology by the Jefferson Angular Momentum collaboration (JAM).

  198. HET Seminar

    "Searching for Ultralight Particles with Black Holes and Gravitational Waves"

    Presented by Masha Baryakhtar, Perimeter Inst. Theor. Phys.

    Wednesday, December 13, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

    The LIGO detection of gravitational waves has opened a new window on the universe. I will discuss how the process of superradiance, combined with gravitational wave measurements, makes black holes into nature's laboratories to search for new light bosons, from axions to dark photons. When a bosonic particle's Compton wavelength is comparable to the horizon size of a black hole, superradiance of these bosons into `hydrogenic' bound states extracts energy and angular momentum from the black hole. The occupation number of the levels grows exponentially and the black hole spins down. One candidate for such an ultralight boson is the QCD axion with decay constant above the GUT scale. Current black hole spin measurements disfavor a factor of 30 (400) in axion (vector) mass; future measurements can provide evidence of a new boson. Particles transitioning between levels and annihilating to gravitons may produce thousands of monochromatic gravitational wave signals, and turn LIGO into a particle detector.

  199. Physics Colloquium

    "The "self-stirred" genome: Bulk and surface dynamics of the chromatin globule"

    Presented by Alexandra Zidovska, New York University

    Tuesday, December 12, 2017, 3:30 pm
    Large Seminar Room, Bldg. 510

    Chromatin structure and dynamics control all aspects of DNA biology yet are poorly understood. In interphase, time between two cell divisions, chromatin fills the cell nucleus in its minimally condensed polymeric state. Chromatin serves as substrate to a number of biological processes, e.g. gene expression and DNA replication, which require it to become locally restructured. These are energy-consuming processes giving rise to nonequilibrium dynamics. Chromatin dynamics has been traditionally studied by imaging of fluorescently labeled nuclear proteins and single DNA-sites, thus focusing only on a small number of tracer particles. Recently, we developed an approach, displacement correlation spectroscopy (DCS) based on time-resolved image correlation analysis, to map chromatin dynamics simultaneously across the whole nucleus in cultured human cells [1]. DCS revealed that chromatin movement was coherent across large regions (4–5μm) for several seconds. Regions of coherent motion extended beyond the boundaries of single-chromosome territories, suggesting elastic coupling of motion over length scales much larger than those of genes [1]. These largescale, coupled motions were ATP-dependent and unidirectional for several seconds. Following these observations, we developed a hydrodynamic theory of active chromatin dynamics, using the two-fluid model and describing the content of cell nucleus as a chromatin solution, which is subject to both passive thermal fluctuations and active (ATP-consuming) scalar and vector events [2]. In this work we continue in our efforts to elucidate the mechanism and function of the chromatin dynamics in interphase. We investigate the chromatin interactions with the nuclear envelope and compare the surface dynamics of the chromatin globule with its bulk dynamics [3]. Furthermore, we explore the rheology of the chromatin inside the cell nucleus using the native subnuclear structures [4]. [1] Zidovska A, Weitz DA, Mitchi

  200. Particle Physics Seminar

    "A Unified Program of Argon Dark Matter Searches: DarkSide-20k and The Global Argon Dark Matter Collaboration"

    Presented by Cristiano Galbiati, Princeton University

    Monday, December 11, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    : Experimenters from four different argon dark matter searches have joined their forces in the the "Global Argon Dark Matter Collaboration" to carry out a unified program for dark matter direct detection. The participants are researchers currently working on the ArDM experiment at LSC; on the DarkSide-50 experiment at LNGS; on the DEAP-3600 experiment at SNOLab; and on the MiniCLEAN experiment at SNOLab. In 2015/2016 The DarkSide-50 experiment at LNGS produced two zero-background science results, along with a comparison of the results obtained with both atmospheric and underground argon fills, demonstrating the ability of large experiments to eliminate background from betas/gammas at the tens of tonne-year exposure. The DEAP-3600 experiment at SNOLAB is the first tonne-scale experiment to achieve both stable operations and an extended physics run. DEAP-3600 has been collecting physics data with over 3 tonnes of argon since late 2016 and published its first results in 2017. Researchers from the four experiments will jointly carry out as the single next step at the scale of a few tens of tonnes the DarkSide-20k experiment. DarkSide-20k was approved in 2017 by the Italian INFN, by the host laboratory LNGS, and by the US NSF. DarkSide-20k is also officially and jointly supported by the three underground laboratories LNGS, LSC, and SNOLab. DarkSide-20k is a 20-tonne fiducial volume dual-phase TPC to be operated at LNGS with an underground argon fill, designed to collect an exposure of 100 tonne×years, completely free of neutron-induced nuclear recoil background and all electron recoil background. DarkSide-20k is set to start operating by 2021 and will have sensitivity to WIMP-nucleon spin-independent cross sections of 1.2 × 10−47 cm2 for WIMPs of 1 TeV/c2 mass, to be achieved during a 5 year run. An extended 10 year run could produce an exposure of 200 tonne×years, with sensitivity for the cross-section of 7.4 × 10&min

  201. Special HET Seminar

    "Effective Theories and Phenomenology of Dark Mesons"

    Presented by Graham Kribs, University of Oregon

    Monday, December 11, 2017, 1:30 pm
    Building 510, Room 2-160

    Hosted by: Hooman Davoudiasl

  202. HET Lunch Discussions

    "A precise determination of the QCD coupling by the ALPHA Collaboration"

    Presented by Mattia Bruno, BNL

    Friday, December 8, 2017, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  203. Particle Physics Seminar

    "Machine Learning Analysis of Ising Worms"

    Presented by Sam Foreman, University of Iowa

    Thursday, December 7, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    Motivated by recent results demonstrating the applicability of machine learning techniques to quantum spin systems, we explore an application of the worm algorithm to the two dimensional Ising model. We begin by presenting the high temperature expansion of the Ising model, which is used to generate equilibrium configurations of "worms" represented as two¬dimensional greyscale images. From these configurations, we are then able to calculate physical quantities of interest. In particular, we are able to identify the logarithmic divergence of the specific heat at the critical temperature. We then propose a complementary approach using machine learning techniques (in particular, principal component analysis, (PCA)) which also successfully identifies the divergent behavior near criticality. Finally, we investigate the behavior of the previously mentioned concepts under a renormalization group coarse¬graining procedure, and present ideas for future research.

  204. RIKEN Lunch Seminar

    "Pushing the boundaries of relativistic fluid dynamics"

    Presented by Jorge Noronha

    Thursday, December 7, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    For nearly a century, dissipative effects have been included in fluid dynamics using gradients of macroscopic quantities such as the temperature and fluid velocity. Recently, results from heavy ion collision experiments and explicit model calculations have pushed the boundaries of relativistic fluid dynamics towards the far-from-equilibrium regime. In this talk I will present calculations of the large order behavior of the gradient expansion, both in kinetic theory and in holography, which have demonstrated that this series has zero radius of convergence. I will discuss the role played by novel non-equilibrium attractor solutions in determining the emergence of fluid dynamic behavior in many-body systems under extreme conditions.

  205. Condensed-Matter Physics & Materials Science Seminar

    "Examples of translational research using thermoelectric oxides"

    Presented by Ryoji Funahashi, National Institute of Advanced Industrial Science & Technology, Japan

    Wednesday, December 6, 2017, 3 pm
    Conference Room, Building 480

    Hosted by: Qiang Li

    We have been relishing a lot of affluence thanks to energy. Fossil energy provides us fun to drive, warmth to escape from cold, brightness of illumination, etc. However consumption of the fossil fuel produces CO2. The amount of CO2 emission will increase with increasing consumption of fossil energy, gas, oil, and coal year by year. The average of total utilizing efficiency of the primary energy is as low as 30 %, with 70 % exhausted to the air as waste heat. It is clear that improved efficiencies of energy conversion systems could have a significant impact on energy consumption and carbon dioxide emission rate. Where a large sum of heat is localized, mechanical conversion systems can be used to generate electricity. However, most sources of waste heat are widely dispersed. Although technologies of storage and transport of such the dilute heat energy have been developed, most waste heat can't be used effectively. Electricity is a convenient form of energy that is easily transported, redirected, and stored, thus there are a number of advantages to the conversion of waste heat emitted from our living and industrial activities to electricity. Thermoelectric conversion is paid attention as the strongest candidate to generate electricity from dilute waste heat. Oxide materials are considered to be promising ones because of their durability against high temperature, low cost for producing etc. The misfit CoO2 compounds show high thermoelectric efficiency at high temperature in air. Thermoelectric modules using p-type Ca3Co4O9, one of the CoO2 compounds and n-type CaMnO3 have been produced [1, 2]. The maximum power density against area of the substrate of the module reaches 4.3 kW/m2 at 973 K of the heat source temperature [3]. Portable power generation units composed of an oxide thermoelectric module. Water circulation and batteries for air cooling are unnecessary for thermoelectric conversion. The units can generate 2-5 W using heat energy with temperature of 300-8

  206. Physics Colloquium

    "Thinking inside the box - hadron resonances in QCD"

    Presented by Jozef Dudek, JLab

    Tuesday, December 5, 2017, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Rob Pisarski

    I will describe how we can make use of the finite box in which lattice QCD calculations are performed to learn something about hadron scattering amplitudes from first principles. These amplitudes contain information about the resonance structure of QCD and hence the spectrum of excited mesons and baryons. I'll present the results of recent calculations in which the lightest scalar, vector and tensor mesons have been studied.

  207. Nuclear Theory/RIKEN seminar

    "Medium modification of jet and jet-induced medium excitation"

    Presented by Shanshan Cao, Wayne State University

    Friday, December 1, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    A coupled linear Boltzmann transport and hydrodynamics model (CoLBT-hydro) is developed for concurrent simulation of jet propagation and hydrodynamic evolution in high-energy nuclear collisions. Diverse microscopic scattering processes (elastic and inelastic) are incorporated for parton showers, and both massive and massless partons are calculated on the same footing. Energy deposition from jets into nuclear matter is treated as source term of hydrodynamic evolution. Within this CoLBT-hydro model, nuclear modification of heavy and light flavor hadrons are simultaneously described. Evidence of jet-induced medium excitation is explored with photon-triggered jets, where significant enhancement of soft hadron production is found due to energy deposition from jets.

  208. HET Lunch Discussions

    "Double Higgs Production in the Complex Singlet Extended Standard Model"

    Presented by Matt Sullivan, University of Kansas

    Friday, December 1, 2017, 12:15 pm
    Orange Room

    Hosted by: Christoph Lehner

  209. HET Seminar

    "Do Electroweak Corrections Violate Factorization?"

    Presented by Ira Rothstein, Carnegie Mellon U

    Wednesday, November 29, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Eder Izaguirre

  210. Particle Physics Seminar

    "The strong CP-problem and axion dark matter searches"

    Presented by Yannis Semertzidis, KAIST and IBS

    Monday, November 27, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chao Zhang

    The strong CP-problem, i.e. why is the neutron EDM experimental limit is at least ten orders of magnitude lower than expected from the theory of QCD is one of the mysteries in physics today. Peccei and Quinn came up with a solution to the strong CP-problem at the expense of requiring an extra pseudo-scalar particle, the axion. It turns out, the axion at a certain mass range is also an ideal dark matter candidate and it can be detected via its conversion to microwave photons in the presence of a strong magnetic field. IBS/CAPP in South Korea, the center for axion and precision physics research of the institute for basic science, was established to elucidate the strong CP-problem and in particular the axion dark matter mystery. I'm going to give an overview of the history of axion dark matter searches, the present status and the plans for answering whether or not axions are a significant part of the dark matter in our galaxy.

  211. Physics Colloquium

    "Numerical Relativity in the Multimessenger Era"

    Presented by Manuela Campanelli, Rochester Institute of Technology

    Tuesday, November 21, 2017, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    The recent discovery of gravitational waves by Advanced LIGO ushered in a new kind of astronomy, one potentially integrating its findings with those obtained from electromagnetic and/or neutrino observations. Multi-messenger astronomy promises to revolutionize our understanding of the universe by providing dramatically contrasting views of the same objects. To understand this unprecedented wealth of observational evidence, computer intensive theoretical calculations of the Einstein field equations, coupled with the equations of magneto-hydrodynamics, are required in order to link data with underlying physics. In this talk, I will provide a review on the recent progress in this exciting field of computational astrophysics. With Advanced LIGO now fully operational and the detection of additional gravitational wave events imminent, we expect that there will be a surge in the number of researchers interested in performing simulations of compact binary mergers.

  212. Nuclear Theory/RIKEN Seminar

    "Higher-order corrections to jet quenching"

    Presented by Yacine Mehtar-Tani, University of Washington

    Friday, November 17, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    The phenomenon of jet quenching in ultra-relativistic heavy ion collisions reveals to effect of substantial finial state interactions which cause QCD jets to lose energy to the quark-gluon plasma (QGP), mainly by induced gluon radiation. In standard analytic approaches to energy loss, jets are approximated by single partons and thus higher-order effects in the strong coupling constant are neglected. This may prove insufficient to reliably extract QGP properties at high pT, where a significant jet suppression was recently reported by the ATLAS collaboration in PbPb collisions at the LHC. In this work we explore higher-order corrections to the inclusive jet spectrum which may be sizable owing to the fact that the probability for a highly virtual parton to split in the medium increases with the jet pT. As the effective number of jet constituents increases, jets are expected to lose more energy than a single color charge. This translates into large logarithmic enhancements of higher-orders in the perturbative series, that need to be resummed. As a result we obtain a Sudakov-like suppression factor which we investigate in the leading logarithmic approximation. We note, however, that the phase space for higher-order corrections is mitigated by coherence effects that relate to the fact that, below a characteristic angular scale, the medium does not resolve the inner jet structure. In this case, the jet lose energy coherently as a single color charge, namely, the primary parton.

  213. HET Lunch Discussions

    "Unified Scenario for Composite Right-Handed Neutrinos and Dark Matter"

    Presented by Pier Paolo Giardino

    Friday, November 17, 2017, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  214. Condensed-Matter Physics & Materials Science Seminar

    "Complementary response of static spin-stripe order and superconductivity to non-magnetic impurities and pressure in cuprates"

    Presented by Zurab Guguchia, Columbia University

    Thursday, November 16, 2017, 1:30 pm
    ISB Bldg. 734, Conference Room 201 (upstairs)

    Hosted by: Emil Bozin

    Cuprate high-temperature superconductors (HTSs) have complex phase diagrams with multiple competing ordered phases. Understanding to which degree charge, spin, and superconducting orders compete or coexist is paramount for elucidating the microscopic pairing mechanism in the cuprate HTSs. In this talk, i will report some novel results of muonspin rotation (μSR), neutron Scattering and magnetization experiments on non-magnetic Zn impurity and hydrostatic pressure effects on the static spin-stripe order and superconductivity in the La214 cuprates [1,2]. Namely, in La2−xBaxCu1−yZnyO4 (0.11 ≤ x ≤ 0.17) and La1.48Nd0.4Sr0.12Cu1−yZnyO4. Remarkably, it was found that in these systems the spin-stripe ordering temperature Tso decreases linearly with Zn doping y and disappears at y ≈ 4 % , demonstrating the extreme sensitivity of static spin-stripe order to impurities within a CuO2 plane. Moreover, Tso is suppressed in the same manner as the superconducting transition temperature Tc by Zn impurities. We also observed the same pressure evolution of both Tc and Tso in La2−xBaxCuO4, while there is an antagonistic pressure evolution of magnetic volume fraction and superfluid density [1,2,3]. These results indicate that static spin-stripe order and SC pairing correlations develop in a cooperative fashion in La214 cuprates. In other words, the existence of the stripe order requires intertwining with the SC pairing correlations, such as occurs in the proposed pair-density wave (PDW) state [4]. [1] Z. Guguchia et. al., Phys. Rev. B 94, 214511 (2016). [2] Z. Guguchia et. al., Phys. Rev. Lett. 119, 087002 (2017). [3] Z. Guguchia et. al., Phys. Rev. Lett. 113, 057002 (2014). [4] E. Fradkin, S.A. Kivelson, and J.M. Tranquada, Rev. Mod. Phys. 87, 457 (2015).

  215. RIKEN Lunch Seminar

    "QCD from gluon, quark, and meson correlators"

    Presented by Mario Mitter, BNL

    Thursday, November 16, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    We present non-perturbative first-principle results for quark-, gluon- and meson 1PI correlation functions of two-flavour Landau-gauge QCD in the vacuum and Yang-Mills theory at finite temperature. They are obtained by solving their Functional Renormalisation Group equations in a systematic vertex expansion, aiming at apparent convergence within a self-consistent approximation scheme. These correlation functions carry the full information about the theory and their connection to physical observables is discussed. The presented calculations represent a crucial prerequisite for quantitative first-principle studies of QCD and its phase diagram within this framework. In particular, we have computed the ghost, quark and scalar-pseudoscalar meson propagators, as well as gluon, ghost-gluon, quark-gluon, quark, quark-meson, and meson interactions and the magnetic and electric components of the gluon propagator, and the three- and four-gluon vertices. Our results stress the crucial importance of the quantitatively correct running of different vertices in the semi-perturbative regime for describing the phenomena and scales of confinement and spontaneous chiral symmetry breaking without phenomenological input. We confront our results for the correlators with lattice simulations and compare our Debye mass to hard thermal loop perturbation theory. Finally, applications to "QCD-enhanced" low-energy effective models of QCD are discussed.

  216. HET Seminar

    "Analysis of a Dilaton EFT for Lattice Data"

    Presented by Thomas Appelquist, Yale University

    Wednesday, November 15, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mattio Bruno

  217. Physics Colloquium

    ""The muon anomalous magnetic moment — A precision test of the standard model""

    Presented by Christoph Lehner, BNL

    Tuesday, November 14, 2017, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Robert Pisarski

    The anomalous magnetic moment of the muon is one of the most precisely determined quantities in particle physics. It is currently known both experimentally and from theory to approximately 1/2 parts per million. Interestingly, there is an approximate 3—4 sigma tension between theory computation and the experimental value (BNL E821) which may hint at new physics beyond the standard model of particle physics. In this talk, I review the current status of a soon-expected improved experimental measurement (FNAL E989) and recent rapid progress in reducing the uncertainty of the standard model theory computation.

  218. Nuclear Physics Seminar

    "Fermilab E-906/SeaQuest: A novel nucleon structure laboratory"

    Presented by Bryan Ramson, University of Michigan

    Tuesday, November 14, 2017, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Oleg Eyser

    SeaQuest is the latest iteration in a series of Fermilab experiments designed to probe nucleon structure using the Drell-Yan process. The most recent ancestor of SeaQuest, E866/NuSea, used the Drell-Yan process to provide the most comprehensive observations of the light-quark flavor asymmetry to date, which suggested significant non-pertubative effects in the nucleon sea. Other measurements concerning cold nuclear matter, J/Psi production, and Drell-Yan angular distributions were conducted as well. SeaQuest aims to complement the flagship NuSea measurement by probing higher seaquark momenta at a lower center-of-mass energy and higher intensity. A summary of the light-quark flavor asymmetry measurement status will be reported as well as the status of various parallel analyses, one of which could have implications for the Boer-Mulders initial state TMD.

  219. Center for Functional Nanomaterials Seminar

    "Using Modeling and Machine Learning to Accelerate High-Throughput Experimental Materials Discovery"

    Presented by Jason R. Hattrick-Simpers, National Institute of Standards and Technology

    Monday, November 13, 2017, 11 am
    CFN, Bldg. 735, Conference Room A, 1st Floor

    Hosted by: Matthew Sfeir

    Over the past 10 years there has been a resurgent interest in the development of novel metallic alloys, both as multiple principle component solid solution alloys, so-called high entropy alloys (HEA) as well as amorphous metallic glasses. Although a number of empirical rules have been proposed for the prediction of potential alloy compositions, calculating their stability and quantifying their properties of interest at operating temperatures from first principles represents a significant challenge. In fact, even high-throughput experimental studies struggle to effectively explore such large composition-processing-property parameter spaces efficiently. Here, I will discuss an approach that seeks to address the rational experimental exploration of such alloys by combining theory, experiment and data science. Our approach is to use insights from the literature, theory, and/or data mining to identify the regions of parameter space most likely to yield interesting materials. We then employ computationally guided high-throughput synthesis techniques to strategically probe composition and processing space. In situ synchrotron diffraction studies yield tens of thousands of data sets describing the evolution of the alloy phase and corrosion products. The data are evaluated using automated knowledge extraction techniques, enabling us to assess our experiments, update the models used to generate the initial lead materials, and plan the next material system to study. In this talk, I will emphasize our recent work using these techniques to investigate phase stability in metallic glasses.

  220. Particle Physics - SB/BNL Joint Cosmo seminar (at BNL)

    "Dark Matter Searches with CCDs and the Sensei Experiment"

    Presented by Dr. Javier Tiffenberg, FNAL

    Thursday, November 9, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Erin Sheldon

  221. Condensed-Matter Physics & Materials Science Seminar

    "Quasiparticle spectra from stochastic many-body methods"

    Presented by Vojtech Vlcek, University of California, Los Angeles

    Thursday, November 9, 2017, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Gabi Kotliar

    I will present new developments and applications of stochastic approaches to electronic structure and many-body perturbation theory, which overcome the steep scaling of conventional deterministic schemes. The general principles of linear-scaling stochastic methods for TDDFT, GW and BSE will be discussed and exemplified on realistic nanoscale systems with more than 5000 valence electrons. The stochastic approaches enable mapping the evolution of optical absorption, spectral functions and quasiparticle energies and lifetimes, as well as the emergence of collective excitations, over the full range from molecules to large bulk-like 3D nanoclusters and 2D layers.

  222. HET Seminar

    "Tomorrow's Colloquium: Joanna Kiryluk: IceCube: Understanding the High Energy Universe with Cosmic Neutrinos"

    Presented by Linda Carpenter, Ohio State University

    Wednesday, November 8, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    Though the Higgs has a non trivial branching fraction -8 percent, to light jets, this is a very hard channel to directly capture with the LHC. We study the Higgs boson (h ) decay to two light jets at the 14 TeV High-Luminosity-LHC (HL-LHC), where a light jet (j ) represents any nonflavor-tagged jet from the observational point of view. The decay mode Higgs to gluons is chosen as the benchmark since it is the dominant channel in the Standard Model, but the bound obtained is also applicable to the light quarks. We estimate the achievable bounds on the decay branching fractions through the associated production V h (V =W±,Z ). Events of the Higgs boson decaying into heavy (tagged) or light (untagged) jets are correlatively analyzed. We find that with 3000 fb-1 data at the HL-LHC corresponds to a reachable upper bound of a few times the SM prediction. Which can ten be turned into a bound on the Higgs couplings to gluons and light quark flavors. A consistency fit also leads to an upper bound on the Higgs to charm coupling. The estimated bound may be further strengthened by adopting multiple variable analyses or adding other production channels.

  223. Updated HET Seminar

    "Capturing Higgs Boson Decays to Light Jets at LHC"

    Presented by Linda Carpenter, Ohio State University

    Wednesday, November 8, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Christopher Murphy

    Though the Higgs has a non trivial branching fraction -8 percent, to light jets, this is a very hard channel to directly capture with the LHC. We study the Higgs boson (h ) decay to two light jets at the 14 TeV High-Luminosity-LHC (HL-LHC), where a light jet (j ) represents any nonflavor-tagged jet from the observational point of view. The decay mode Higgs to gluons is chosen as the benchmark since it is the dominant channel in the Standard Model, but the bound obtained is also applicable to the light quarks. We estimate the achievable bounds on the decay branching fractions through the associated production V h (V =W±,Z ). Events of the Higgs boson decaying into heavy (tagged) or light (untagged) jets are correlatively analyzed. We find that with 3000 fb-1 data at the HL-LHC corresponds to a reachable upper bound of a few times the SM prediction. Which can ten be turned into a bound on the Higgs couplings to gluons and light quark flavors. A consistency fit also leads to an upper bound on the Higgs to charm coupling. The estimated bound may be further strengthened by adopting multiple variable analyses or adding other production channels.

  224. Physics Colloquium

    "Building an entanglement sharing quantum network"

    Presented by Professor Eden Figueroa, Stony Brook University

    Tuesday, November 7, 2017, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Andrei Nomerotski

    In the first part of our talk we will show how to produce photonic quantum entanglement and how to store it and distribute it by optically manipulating the properties of room temperature atomic clouds. We will discuss our recent experiments in which several quantum devices are already interconnected forming an elementary quantum cryptographic network. We will also discuss our progress regarding the construction of an entanglement sharing link between Stony Brook and BNL. In the second part we will show our progress regarding the construction of an analog quantum computer capable of simulating relativistic dynamics using atoms and quantized light. We will show how our device is already capable of simulating Dirac and Jackiw-Rebbi Hamiltonians as well as the road map towards simulating Quantum Field Theory Hamiltonians.

  225. Condensed-Matter Physics & Materials Science Seminar

    "Proximity effects in cuprate/manganite multilayers"

    Presented by Christian Bernhard, University of Fribourg, Switzerland

    Monday, November 6, 2017, 1:30 pm
    ISB Bldg. 734 Seminar Room 201 (upstairs)

    Hosted by: Chris Homes

    Recently we observed an intriguing, magnetic-filed-induced insulator-to-metal transition in YBa2Cu3O7/Pr1-xCaxMnO3 (YBCO/PCMO) multilayers [1]. In the low field regime, the response of these multilayers is highly resistive and resembles the one of granular superconductors or frustrated Josephson-networks. Notably, a coherent superconducting response can be restored with a large magnetic field. The latter also suppresses the charge/orbital order of the PCMO layers towards a ferromagnetic state. This coincidence suggests an intimate relationship between the insulator-to-superconductor transition in the YBCO layer and the suppression of the charge/orbital order in the PCMO. I will discuss the evidence, based on resonant x-ray scattering experiments, that the latter induces (or strongly enhances) a static Cu-CDW order in YBCO that is intertwined with superconductivity. [1] B.P.P. Mallett et al., Phys. Rev. B 94, 180503(R) (2016).

  226. Nuclear Theory/RIKEN Seminar

    "Proton radius puzzle"

    Presented by Gerald Miller, University of Washington

    Friday, November 3, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

  227. Updated HET Lunch Discussions

    ""Dark Parity Violation After Qweak and Future Neutrino Physics Discussion" (Neutrino Discovery Initiative)"

    Presented by William J. Marciano, BNL

    Friday, November 3, 2017, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

    To participate via BlueJean connection, please click on the following link: https://bluejeans.com/753838707/7269 Meeting ID: 753 838 707 Participate Passcode: 7269

  228. HET Lunch Discussions

    "Dark Parity Violation After Qweak and Future Neutrino Physics Discussion"

    Presented by William J. Marciano, BNL

    Friday, November 3, 2017, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  229. Condensed-Matter Physics & Materials Science Seminar

    "Wandering amongst the Feynamn diagrams"

    Presented by Nikolay Prokofiev, University of Massachusetts-Amherst

    Friday, November 3, 2017, 11 am
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Igor Zaliznyak

    Feynman diagrams are the most celebrated and powerful tool of theoretical physics usually associated with the analytic approach. I will argue that diagrammatic expansions are also an ideal numerical tool with enormous and yet to be explored potential for solving interacting many-body systems by direct simulation of Feynman diagrams (bare or skeleton) for the proper self-energies and polarization operators up to high order. Though the original series based on are propagators are sign-alternating and often divergent one can determine the answer behind them by using proper series re-summation techniques and working with skeleton diagrams, i.e. by making the entire scheme self-consistent. The bottom line is that the diagrammatic Monte Carlo approach generically solves the computational complexity for interacting fermionic systems. In terms of physical applications, I will disucss results for the Hubbard model, resonant fermi gas at unitarity, and stability of Dirac liquid against strong Coulomb interaction in graphene.

  230. Particle Physics Seminar

    "UCNtau: A magneto-gravitational trap measurement of the free neutron lifetime"

    Presented by Robert Pattie, Los Alamos National Laboratory

    Thursday, November 2, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Xin Qian

    The neutron is the simplest nuclear system that can be used to probe the structure of the weak interaction and search for physics Beyond the Standard Model. Measurements of neutron ?-decay observables are sensitive to scalar and tensor interactions in the weak force which are not present in the Standard Model. The lifetime of the neutron ?n is an important parameter for Big-Bang Nucleo-synthesis models, solar fusion models, and absolute neutrino scattering cross-sections, and can be used to test the unitarity of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Presently, the two typical methods used to measure the neutron lifetime, cold neutron beam measurements and stored ultracold neutron (UCN) measurements, disagree by roughly 4?. This discrepancy motivates the need for new measurements with complementary systematic uncertainties to previous efforts. The UCN? experiment uses an asymmetric magneto-gravitational UCN trap with in situ counting of surviving neutrons to measure the neutron lifetime. Previous bottle experiments confined UCN in a material storage vessel creating a significant correction due to losses resulting from the material UCN interactions. The magnetic and gravitational confinement of the UCN minimizes losses due to material interactions. Additionally, UCN? uses a detection system that is lowered into the storage volume which avoids emptying the surviving UCN into an external detector. This minimizes any possible transport related systematics. This in situ detector also enables counting at various heights in the vessel, which provides information on the trapped UCN energy spectrum, quasi-bound orbits, and possible phase space evolution. I will present the physics motivation for precision neutron physics, a description of the UCN? experiment, the results of data collected during the 2016-2017 accelerator cycle which resulted in a value of τn=877.7±(0.7) stat (+0.3/−0.1) sys in agreement with previous material bottle

  231. RIKEN Lunch Seminar

    "Rotating Dirac fermion in Magnetic field in 1+2 and 1+3 dimensions"

    Presented by Yizhuang Liu, Stony Brook University

    Thursday, November 2, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

  232. HET/RIKEN Seminar

    "Calculation of the electric dipole moment with the gradient flow"

    Presented by Andrea Shindler, Michigan State University

    Wednesday, November 1, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

  233. HET Lunch Discussions

    "A statistical approach to Higgs couplings in the SMEFT, 1710.02008"

    Presented by Chris Murphy, BNL

    Friday, October 27, 2017, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  234. Particle Physics Seminar

    "Search for dark matter at the CMS experiment"

    Presented by Adish Vartak, University of California San Diego

    Friday, October 27, 2017, 10 am
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    There is an extensive, on-going dark matter search program at the LHC that explores several different types of possible interactions between WIMP-like dark matter and standard model particles. The dark matter searches at the LHC are complementary, and in case of certain models, significantly more sensitive than the direct and indirect dark matter searches. In this talk I will discuss several key dark matter searches being pursued by the CMS collaboration. These cover a wide variety of final states in which dark matter particles are produced in association with one or more energetic, visible objects in the detector resulting in 'MET+X' signatures. Furthermore, I will also discuss the constraints set on dark matter interactions by certain resonance searches.

  235. Particle Physics Seminar

    "Observation of Coherent Elastic Neutrino-Nucleus Scattering by COHERENT"

    Presented by Kate Scholberg, Duke University

    Thursday, October 26, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Xin Qian

    Coherent elastic neutrino-nucleus scattering (CEvNS) is a process in which a neutrino scatters off an entire nucleus at low momentum transfer, and for which the observable signature is a low-energy nuclear recoil. It represents a background for direct dark matter detection experiments, as well as a possible signal for astrophysical neutrinos. Furthermore, because the process is cleanly predicted in the Standard Model, a measurement is sensitive to beyond-the-Standard-Model physics, such as non-standard interactions of neutrinos. The process was first predicted in 1973. It was measured for the first time by the COHERENT collaboration using the high-quality source of pion-decay-at-rest neutrinos from the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory and a CsI[Na] scintillator detector. This talk will describe COHERENT's recent 6.7-sigma measurement of CEvNS, the status and plans of COHERENT's suite of detectors at the SNS, and future physics reach.

  236. RIKEN Lunch Seminar

    "Approach to equilibrium of quarkonium in quark-gluon plasma"

    Presented by Xiaojun Yao, BNL

    Thursday, October 26, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    Quarkonium can be used as a probe of quark-gluon plasma (QGP) in heavy ion collisions. The production process is complicated by several factors: plasma screening effect, in-medium dissociation and recombination, cold nuclear matter effect and feed-down contributions. In this talk, I will present a set of Boltzmann transport equations that govern the in-medium evolution of the heavy quark and quarkonium system. The dissociation and recombination rates are calculated from potential non-relativistic QCD at leading order. I will explain how the system reaches equilibrium in a QGP box and show how the system evolves under a boost invariant longitudinal expansion. I will argue that the angular distribution of quarkonium probes the stages at which recombination occurs. The presented framework will be extended in future work to include other factors influencing quarkonium production.

  237. Condensed-Matter Physics & Materials Science Seminar

    "Theory and Computation Guided Discovery of New Thermoelectric Materials"

    Presented by Vladan Stevanovic, Colorado School of Mines & National Renewable Energy Laboratory

    Wednesday, October 25, 2017, 1:30 pm
    ISB Bldg. 734, Conf. Rm. 201 (upstairs)

    Hosted by: Cedomir Petrovic

    Progress in the widespread adoption of all solid heat-to-electricity technologies has largely been hindered by the absence of suitable thermoelectric materials. In pursuit for new thermoelectrics recent advances in large-scale deployment of first principles calculations could be useful in identifying new promising material systems. However, the need to predict electron and phonon transport properties with sufficient accuracy renders direct assessment of the thermoelectric figure of merit (zT) for large numbers of systems unfeasible. This is true even in the case of relatively simple semiconductor materials, which could be described by the computationally inexpensive single particle theories such as density functional theory (DFT). While the state-of-the-art DFT based approaches to charge carrier and heat transport of semiconductors can deliver desired accuracy, they are currently limited to relatively simple chemistries and/or case-by-case studies. In this talk I will discuss integrated theory-computation-experiment efforts in developing a robust set of material descriptors that: (1) are rooted in the Boltzmann transport theory, but do not rely on classic and largely inapplicable constant relaxation time or constant mean free path approximations, (2) are computationally tractable allowing material searches across large chemical spaces, and (3) are sufficiently accurate to provide reliable predictions. Our approach is demonstrated to correctly identify known thermoelectric materials1 and reliably suggest new and promising candidate semiconductors.2 At the end, I will review successes and failures in our quest for new thermoelectrics, and discuss dopability of semiconductors as the critical outstanding challenge in achieving high zT materials. 1. Yan, P. Gorai, B. Ortiz, S. Miller, S. A. Barnett, T. Mason, V. Stevanovic, and E. S. Toberer, "Material descriptors for thermoelectric performance", Energy Environ. Sci. 2. P. Gorai, V. Stevanovic, and E. Tobe

  238. Physics Colloquium

    "The Path Forward in Gravitational-wave astronomy"

    Presented by Zsuzsa Marka, Columbia University

    Tuesday, October 24, 2017, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    On August 17, 2017 the merger of two neutron stars was detected in the form of gravitational-waves by LIGO/Virgo. As a result of over a decade long preparation for multimessenger observations the event was also seen electromagnetically across the full spectrum. The history and future of the multimessenger effort using gravitational-waves will be discussed from an instrumentalist viewpoint.

  239. Nuclear Physics Seminar

    "To CME or not to CME? Implications of recent charge separation measurements in p(d)+Au, Au(Cu)+Au and U+U collisions for the chiral magnetic effect in heavy ion collisions"

    Presented by Roy Lacey, Stony Brook University

    Tuesday, October 24, 2017, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Bjoern Schenke

    The observation of charge separation induced by the Chiral Magnetic Effect (CME), could provide crucial insights on anomalous transport and the interplay of chiral symmetry restoration, axial anomaly, and gluonic topology in the Quark Gluon Plasma (QGP) produced in heavy ion collisions. I will discuss recent differential charge separation measurements,for p(d)+Au, Au(Cu)+Au and U+U, with a correlator specifically designed to give discernible responses to CME-driven charge separation and non-CME backgrounds. Measurements which span the beam energy range Root_s = 19.5 - 200 GeV will be presented. The d(p)+Au results are observed to be consistent with the reduced magnetic field strength and the essentially random B-field orientations expected in these collisions. In contrast, the Au(Cu)+Au and U+U measurements validate the presence of CME-driven charge separation quantified by the Fourier dipole coefficient a1. Ongoing attempts for CME-signal quantification, as well as implications for the upcoming RHIC isobar run, will be discussed as well.

  240. Condensed-Matter Physics & Materials Science Seminar

    "Pressure-driven collapse of Jeff=1/2 electronic state in a honeycomb iridate"

    Presented by Young-June Kim, University of Toronto, Canada

    Friday, October 20, 2017, 3 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Igor Zaliznyak

    Orbital and spin degrees of freedom in heavy transition metal compounds can be locked into each other due to strong spin-orbit coupling. The magnetism in this case is described by an effective total angular momentum jeff=1/2 rather than usual spin angular momentum. Furthermore, these jeff=1/2 moments residing on a honeycomb lattice can be coupled through bond-dependent Kitaev interactions. Magnetic properties of some honeycomb lattice iridates, such as Na2IrO3 and Li2IrO3 have been extensively investigated to examine whether Kitaev quantum spin liquid is realized in these compounds. However, the applicability of the jeff=1/2 local moment model in real materials have not been critically scrutinized experimentally. A combination of x-ray absorption spectroscopy, x-ray diffraction, and resonant inelastic x-ray scattering experiments on a honeycomb lattice Li2IrO3 reveals that the jeff=1/2 picture breaks down under high pressure, and electrons take on more itinerant character under this condition.

  241. Nuclear Theory/RIKEN Seminar

    "Quantization of three-body scattering amplitude in isobar formulation"

    Presented by Maxim Mai, George Washington University

    Friday, October 20, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Chun Shen

    In the so-called isobar parametrization the three-particle states are populated via an interacting two-particle system (resonant or non-resonant), and a spectator. Using this parametrization, we derive the isobar-spectator interaction such that the three-body Unitarity is ensured exactly. In the first part of my talk I will show the major steps of this derivation. (arXiv:1706.06118) The second part of the talk will be dedicated to the finite-volume implementation of the framework (arXiv:1709.08222). Imaginary parts in the infinite volume, dictated by Unitarity, determine the dominant power-law finite volume effects to ensure the correct 3-body quantization condition. Furthermore, various building blocks of the 3->3 amplitude in the finite volume can become singular. However, when all contributions are summed-up, only genuine 3-body singularities remain. I will demonstrate the corresponding cancellation mechanisms explicitly for the simplified case of only one S-wave isobar.

  242. Particle Physics Seminar

    "Study of the Higgs properties in the H->ZZ*->4l channel with the ATLAS detector"

    Presented by Gaetano Barone, Brandeis University

    Thursday, October 19, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    Recent measurements of the Higgs boson properties in the four lepton channel for 36.1 fb-1 of proton—proton collisions at 13 TeV using the ATLAS detector will be presented. The measurements include the Higgs boson mass as well as inclusive, fiducial and differential cross sections and, constraints on Higgs boson production couplings. The results are interpreted within the Standard Model and various extensions.

  243. RIKEN Lunch Seminar

    "Lattice QCD and Neutrino Physics"

    Presented by Aaron Meyer, HET Group

    Thursday, October 19, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Enrico Rinaldi

    The nucleon axial form factor is a dominant contribution to systematic uncertainties in neutrino oscillation studies. The most commonly used model parametrization of the axial form factor has uncontrolled and underestimated systematic errors. First-principles computations from lattice QCD have the potential to control theory errors by disentangling the effects of nuclear corrections from the nucleon amplitudes. In this talk, I discuss fits to the axial form factor with deuterium bubble chamber data using the model-independent $z$ expansion parameterization. I then present preliminary results for a blinded lattice QCD calculation of the nucleon axial charge $g_A$ with physical light quark masses. This calculation is being done with the Highly Improved Staggered Quark (HISQ) action and 2+1+1 flavors of sea quarks.

  244. Environmental & Climate Sciences Department Seminar

    "Desert Dust, Wildfire Smoke, Volcanic Ash, Urban and Industrial Pollution – Grasping the Role Particles Play in Global Climate and Regional Air Quality"

    Presented by Ralph Kahn, NASA Goddard Space Flight Center

    Thursday, October 19, 2017, 11 am
    Conference Room Bldg 815E

    Hosted by: Steve Schwartz

    Airborne particles are ubiquitous components of our atmosphere, originating from a variety of natural and anthropogenic sources, exhibiting a wide range of physical properties, and contributing in multiple ways to regional air quality as well as regional-to-global-scale climate. Most remain in the atmosphere for a week or less, but can traverse oceans or continents in that time, carrying nutrients or disease vectors in some cases. Bright aerosols reflect sunlight, and can cool the surface; light-absorbing particles can heat the atmosphere, suppressing cloud formation or mediating larger-scale circulations. In most cases, particles are required to collect water vapor as the initial step in cloud formation, so their presence (or absence) and their hygroscopic or hydrophilic properties can affect cloud occurrence, structure, and ability to precipitate. Grasping the scope and nature of aerosol environmental impacts requires understanding microphysical-to-global scale processes, operating on timescales from minutes to days or longer. Satellites are the primary source of observations on kilometer-to-global scales. Spacecraft observations are complemented by suborbital platforms: aircraft in situ measurements and surface-based instrument networks that operate on smaller spatial scales, some on shorter timescales. Numerical models play a third key role in this work — providing a synthesis of current physical understanding with the aggregate of measurements, and allowing for some predictive capability. This presentation will focus on what we can say about aerosol amount and type from space. Constraining particle "type" is at present the leading challenge for satellite aerosol remote sensing. We will review recent advances and future prospects, including the strengths and limitations of available approaches, and current work toward better integrating measurements with models to create a clearer picture of aerosol environmental impacts, globally.

  245. HET Seminar

    "Semileptonic decays of B_(s) mesons to light pseudoscalar mesons with lattice QCD"

    Presented by Zechariah Gelzer, Iowa University

    Wednesday, October 18, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Mattia Bruno

  246. Particle Physics Seminar

    "The R&D and Mass Production of 20"MCP-PMT for Neutrino Detection"

    Presented by Dr. Sen Qian, IHEP China

    Monday, October 16, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Xin Qian

    Researchers at IHEP, Beijing have conceived a new concept of MCP-PMT several years ago. The small MCP (Microchannel Plate) units replace the bulky Dynode chain in the tranditional large PMTs for better photoelectron detection. After three years R&D, a number of 8 inch prototypes were produced and their performance was carefully tested at IHEP in 2013 by using the MCP-PMT evaluation system built at IHEP. The 20 inch prototypes were followed in 2014, and its' performance were improving a lot in 2015. Compensating the PMT performances with fiducially volume convert all specifications to cost, radioactivity, dark noise, TTS, the JUNO ordered 15000 pic 20-inch MCP-PMT from the NNVT in Dec.2015. In 2016, the MCP-PMT collaboration group finished to build the mass production line in Nanjing at the end of 2016, and finished the batch test system in the same place within 100 days at the beginning of 2017. From 2017 to 2019, all the 20-inch MCP-PMT will be produced and tested one by one in NNVT for JUNO. This presentation will talk about the R&D process and mass production, batch test result of the first 2K pieces of MCP-PMT prototypes for JUNO.

  247. Condensed-Matter Physics & Materials Science Seminar

    "Domain walls and phase boundaries - new nanoscale functional elements in complex oxides"

    Presented by Jan Seidel, UNSW Sydney

    Monday, October 16, 2017, 1:30 pm
    Bldg. 480, Conference Room

    Hosted by: Myung-Geun Han

    Topological structures in functional materials, such as domain walls and skyrmions, see increased attention due to their properties that can be completely different from that of the parent bulk material [1]. I will discuss recent results on multiferroic phase boundaries, domain walls in BiFeO3 [2, 3, 4, 5, 6] using SPM, TEM and ab-initio theory, and discuss future prospects [7]. References [1] J. Seidel (ed.), Topological structures in ferroic materials: domain walls, skyrmions and vortices, ISBN: 978-3-319-25299-5, Springer, Berlin (2016) [2] P. Sharma, et al., Scientific Reports 6, 32347 (2016) [3] P. Sharma, et al., Advanced Electronic Materials 2, 1600283 (2016) [3] J. Seidel, et al., Advanced Materials 26, 4376 (2014) [4] Y. Heo, et al., Advanced Materials 26, 7568 (2014) [5] Y. Heo et al., ACS Nano, DOI: 10.1021/acsnano.6b07869 (2017) [6] P. Sharma, et al., Advanced Materials Interfaces 3, 1600033 (2016) [7] J. Seidel, Nature Nanotechnology 10, 190 (2015)

  248. Nuclear Theory/RIKEN Seminar

    "What can we learn from flow observables in heavy-ion collisions?"

    Presented by Jacquelyn Noronha-Hostler, Rutgers University

    Thursday, October 12, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Chun Shen

    The Quark Gluon Plasma (QGP), nature's first and most perfect liquid, has been successfully reproduced in heavy-ion collisions at RHIC and the LHC. The dynamics of the QGP can be well described by relativistic viscous hydrodynamics, allowing for precise comparisons to experimental data in order to extract the properties of the QGP. While a small shear viscosity is well-established, questions still remain regarding the precise initial state, the temperature dependence of viscosity, the smallest system that displays QGP-like properties, and the equation of state at large densities. In this talk, the various flow harmonic observables are analyzed to help answer these remaining questions.

  249. Particle Physics Seminar

    "SB/BNL Joint Cosmo Seminar (at Stony Brook)"

    Presented by Chang Feng, UC Irvine

    Wednesday, October 11, 2017, 1:30 pm
    Stony Brook

    Hosted by: Neelima Sehgal

  250. HET Lunch Discussions

    "Repulsion of Dark Matter and Null Direct Signals"

    Presented by Hooman Davoudiasl, BNL

    Friday, October 6, 2017, 12:15 pm
    Building 510, Room 2-160

    Hosted by: Christoph Lehner

  251. HET Seminar

    "Flavorful Higgs bosons"

    Presented by Wolfgang Altmannshofer, Cincinnati University

    Wednesday, October 4, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Sally Dawson

    Measurements of Higgs production and decays have revealed that most of the mass of the weak gauge bosons is due to the 125 GeV Higgs. Similarly, we know that the Higgs is at least partially responsible for giving mass to the top and bottom quarks and the tau lepton. Much less is known about the origin of mass for the first two generations. In this talk, I will discuss a framework in which the first and second generation masses originate from a second source of electroweak symmetry breaking and outline the phenomenological implications.

  252. Nuclear Physics Seminar

    "The nature of flow fluctuations, from pp to A+A, and back again"

    Presented by Mingliang Zhou, Stony Brook University

    Tuesday, October 3, 2017, 11 am
    Small Seminar Room, Bldg. 510

    Hosted by: Jiangyong Jia

    In recent years, there have been rapid progresses in our understanding of the event-by-event flow fluctuation, which provides direct insight into the fluctuations in the initial geometry. I will start my talk by briefly discussing the flow (collectivity) and its fluctuation in small systems pp and p+Pb, using the newly-proposed subevent cumulant method, which is able to suppress the non-flow background effectively. I will show there is significant fluctuation of elliptic flow $v_2$ in pp and non-Gaussian fluctuation of triangular flow $v_3$ in p+Pb. Moving from small to large systems, STAR collaboration recently has shown different behaviors of cumulant $c_2\{4\}$ between Au+Au and U+U in ultra-central collisions, which is believed to support the different geometry fluctuations. By presenting the newest ATLAS flow measurements in ultra-central collisions, together with detailed MC Glauber studies, I will explain why sign change of $c_2\{4\}$ is observed and its implications. In the end, I will go back to small systems and discuss the potential impact of centrality resolution on pp flow measurements.

  253. Particle Physics Seminar

    "Latest Results from the T2K Experiment"

    Presented by Kendall Mahn, Michigan State University

    Friday, September 29, 2017, 3:30 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Xin Qian

    One of the most promising investigations of beyond-the-Standard-Model physics has been the study of neutrino oscillation, that is, the conversion of neutrinos from one flavor to another as they propagate. While neutrino oscillation is studied in a wide variety of experiments, accelerator based experiments, such as T2K, use a muon neutrino or antineutrino beam as a source to look for electron (anti)neutrino appearance, muon neutrino disappearance. The source also is used to make measurements of neutrino interactions and search for exotic physics. This talk will describe a recent analysis of both neutrino and antineutrino beam data from T2K. Comparisons between neutrino and antineutrino event rates provide a tantalizing window on possible CP violation in the neutrino sector. The talk will also highlight the increasingly important role of systematic uncertainty assessment for T2K and other future measurements of CP violation with accelerator beams.

  254. Nuclear Theory/RIKEN Seminar

    "QCD on a small circle"

    Presented by Aleksey Cherman, University of Washington

    Friday, September 29, 2017, 2 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Heikki Mantysaari

    Recent developments have shown that QCD-like theories can be engineered to remain in a confined phase when compactified on an arbitrarily small circle, where their features may be studied quantitatively in a controlled fashion. I'll explain how a non-perturbative mass gap and chiral symmetry breaking, which are both historically viewed as prototypical strong coupling effects, appear from systematic weak-coupling calculations. Then I'll describe the rich spectrum of hadronic states, including glueball, meson, and baryon resonances in the calculable small-circle context.

  255. Particle Physics Seminar

    "Beauty and charm decays and physics beyond the Standard Model: an experimentalist perspective"

    Presented by Marina Artuso, Syracuse University

    Thursday, September 28, 2017, 3 pm
    Small Seminar Room, Bldg. 510

    Hosted by: Alessandro Tricoli

    The Standard Model provides a comprehensive explanation for a vast array of data collected at different experiments. Nonetheless fundamental questions remain unanswered and the search for a more complete theory is still a coveted goal of particle physics. Recently, tensions with standard model predictions have been uncovered in several experimental observables in b-hadron decays at LHCb. I will discuss the data, possible implications, and the connection with other experimental programs such as study of kaon rare decays and neutrino mixing and CP violation

  256. Condensed-Matter Physics & Materials Science Seminar

    "Suppression of weak ferromagnetism in ultrathin iridates by interfacial engineering of octahedral rotations"

    Presented by Yuefeng Nie, Nanjing University, China

    Thursday, September 28, 2017, 1:30 pm
    ISB Bldg. 734 Conf. Rm. 201 (upstairs)

    Hosted by: Weiguo Yin

    Layered iridates, Srn+1IrnO3n+1, have drawn great attention since they share remarkable similarities with high-Tc cuprates, including layered crystalline structure, (pseudo) spin ½ states, antiferromagnetic (AFM) Mott insulating ground state, Fermi arcs, and V shape energy gap, etc. Nonetheless, direct evidences of superconductivity such as zero resistivity and Meissner effect are still lacking up to date. The strong spin-orbit coupling and IrO6 octahedral rotations in 5d iridates result in a canted AFM ground state with weak ferromagnetic moments in each IrO2 plane. Here, we propose to suppress the weak ferromagnetism by suppressing the octahedral rotations in iridates, which may facilitate the Cooper pairing. Using a combination of reactive molecular beam epitaxy (MBE), in situ angleresolved photoemission spectroscopy (ARPES) and first principle calculations, we investigate the evolution of octahedral rotations, electronic structure and magnetic ordering in ultra-thin SrIrO3 films grown on (001) SrTiO3 substrate. Our experimental results and theoretical calculations show that octahedral rotations and weak ferromagnetic moments are fully suppressed in 1 and 2 unit cell thick SrIrO3 films through interfacial clamping effects. If time allows, I will also present our recent work on the new understanding of RHEED oscillations in the growth of oxides and the chemically specific termination control of oxide interfaces via layerby- layer mean inner potential engineering.

  257. RIKEN Lunch Seminar

    "Color Memory, Large Gauge Transformations, and Soft Theorems in Yang-Mills Theory"

    Presented by Monica Pate, Harvard University

    Thursday, September 28, 2017, 12:30 pm
    Building 510, Room 2-160

    Hosted by: Hiromichi Nishimura

    An infinite dimensional symmetry group which governs the infrared sectors of gauge and gravity theories has been recently discovered. This symmetry can be established both from an asymptotic symmetry analysis as well as from the corresponding Ward identities which are quantum field theoretic soft theorems. Moreover, the spontaneous breaking of these symmetries induces vacuum transitions which are detectable by charged particles through the so-called memory effect. In this seminar, I will explain the precise equivalence between asymptotic symmetries, soft theorems and memory effects in the context of tree level Yang-Mills. In particular, in this context the soft gluon theorem is Ward identity of a large gauge symmetry, whose action on the vacuum can be measured from the relative color charge of colored detectors.

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