May 2016  

Sunday  Monday  Tuesday  Wednesday  Thursday  Friday  Saturday 
1

2

3

4 
5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

MAY
31
Tuesday
Nuclear Seminar
"Global Hyperon Polarization in Semicentral Heavy Ion Collisions Measured by STAR"
Presented by Mike Lisa, Ohio State University
11 am, Small Seminar Room, Bldg. 510
Tuesday, May 31, 2016, 11:00 am
Hosted by: 'Oleg Eyser'
Noncentral collisions between ultrarelativistic heavy ions involve thousands of hbar of angular momentum. Some of this angular momentum may be transferred to the quarkgluon plasma through shear forces that generate a vortical substructure in the hydrodynamic flow field. Understanding this fundamental femtoscopic substructure may be crucial, as we move beyond boostinvariant scenarios and rely more on sophisticated threedimensional viscous models of the plasma. The vortical nature of the system is expected to polarize the spins of hadrons that eventually emerge. Lambda and AntiLambda hyperons, which reveal their polarization through their decay topology, should be polarized similarly in the direction of the system's angular momentum. These same collisions are also characterized by dynamic magnetic fields with magnitude as large as 10^{14} Tesla. Magnetic effects have been the focus of intense study in recent years due to their relevance to the Chiral Magnetic Effect (CME) and other novel phenomena. A splitting between Lambda and AntiLambda polarization may signal a magnetic coupling and provide a quantitative estimate of the field strength at freeze out. Physically, this strength depends on the conductivity of the QGP. The STAR Collaboration has made the first observation of global hyperon polarization along the direction of the angular momentum in noncentral Au+Au collisions at Beam Energy Scan energies. Our preliminary results indicate that the QGP created at RHIC is the highestvorticity fluid ever created in the laboratory. A magnetic splitting is hinted at, but the improved statistics and resolution achievable with future runs are required to make a definitive measurement of the magnetic field.
JUN
8
Wednesday
Long Island Chapter: American Nuclear Society
"Cheating Scandal at Naval Nuclear Power Training Unit"
Edward Sierra, BNL
6 pm, Brickhouse Brewery, Patchogue, NY
Wednesday, June 8, 2016, 6:00 pm
America's submarines and aircraft carriers rely on nuclear reactors as well as nuclear technicians, power plant operators, and subsystems specialists to keep them running. The men and women of the US Navy Nuclear Propulsion Program (NNPP) operate and maintain the most formidable fleet of nuclearpowered submarines and aircraft carriers on the planet. These sailors are among the best and brightest in America's Navy. However, an exam cheating scandal was reported in 2014 at the Naval Nuclear Power Training Unit at Charleston, SC. From his perspective as a graduate of the Naval Nuclear Power School, Ed Sierra will provide an overview of this demanding school and the 2014 cheating scandal, which he obtained by exercising the Freedom of Information Act. More specifically, he will discuss the details involving a ring of cheating among the instructors that went on for years.
JUN
21
Tuesday
Physics Colloquium
"Sterile Neutrinos as the Origin of Dark and Baryonic Matter"
Presented by Mikhail Shaposhnikov, EPFL
3:30 pm, Large Seminar Room, Bldg. 510
Tuesday, June 21, 2016, 3:30 pm
Hosted by: 'Robert Pisarski'
I will discuss how three sterile neutrinos alone can simultaneously explain neutrino oscillations, the observed dark matter, and the baryon asymmetry of the Universe without new physics above the Fermi scale. The experimental prospects to search for these particles will be outlined.
JUN
24
Friday
Nuclear/Riken Theory Committee
"On Pressure Isotropization in HeavyIon Collisions"
Presented by Bin Wu, The Ohio State University
2 pm, Small Seminar Room, Bldg. 510
Friday, June 24, 2016, 2:00 pm
Hosted by: ''Soeren Schlichting''
In this talk, I would like to start with a brief introduction to nonequilibrium quantum field theory in the SchwingerKeldysh formalism. This formalism provides a systematic way to study isotropization and other timedependent nonequilibrium (and equilibrium) phenomena in heavyion collisions. I shall first discuss the foundation of classical field approximations (CSA), which is an important tool to study the evolution at very early stages. It is, however, found to be nonrenormalizable. This helps us understand better the applicability of such an approximation. it is now wellknown that isotropization can not be established before the breakdown of the CSA. We then use another approximation, the quasiparticle approximation (the Boltzmann equation), to study the isotropization in a scalar field theory. Our result shows explicitly the importance of quantum effects. Motivated by these observations, we have been studying whether the isotropization can be reached before the dense system of gluons, produced in the collisions of two big nuclei, becomes too dilute to be studied perturbatively in the SchwingerKeldysh formalism. Some preliminary results shall be reported.
JUN
28
Tuesday
Nuclear Physics Seminar
"Two Photon Exchange and the Proton Form Factor Problem"
Presented by Lawrence Weinstein, Old Dominion University
11 am, Small Seminar Room, Bldg. 510
Tuesday, June 28, 2016, 11:00 am
Hosted by: 'Oleg Eyser'
The electromagnetic form factors of the proton as measured by polarized and unpolarized electron scattering experiments differ by up to a factor of three at large momentum transfer. Calculations show that this discrepancy can be reconciled by treating the interaction in 2nd Born Approximation, i.e., including two photon exchange (TPE). While calculation of TPE effects is highly model dependent, these effects can be measured directly by comparing elastic electronproton and positronproton scattering. Three experiments, TPE at Jefferson Lab, VEPP3 at Novosibirsk, and OLYMPUS at DESY, measured this. VEPP3 and OLYMPUS used alternating monochromatic e+ and e beams in storage rings; TPE created a tertiary mixed simultaneous e+/e beam covering a wide range of energies. This talk will present the proton form factor problem, the experimental effort to measure the positronelectron ratio (with special emphasis on the Jefferson Lab experiment), and the results.
RIKEN Lunch Seminar
"Lefschetzthimble path integral for studying the sign problem and Silver Blaze phenomenon"
Presented by Yuya Tanizaki, RBRC
Thursday, May 26, 2016, 12:30 pm
Building 510, Room 2160
Hosted by: 'Hiroshi Ohki'
Recently, PicardLefschetz theory gets much attention in the context of the sign problem, because it enables us to study the system with the complex classical action nonperturbatively by employing the semiclassical analysis. In this seminar, after its brief introduction, I will apply it to the onesite Hubbard model. This model has a severe sign problem, which looks quite similar to that of the finitedensity QCD at low temperatures. By solving this model using the Lefschetzthimble path integral, we are trying to understand the structure of the sign problem of finitedensity QCD. Especially, I give a qualitative picture (or speculation) about the earlyonset problem of the baryon number density, called the baryon Silver Blaze problem. The complex Langevin method will also be discussed if time allows.
High Performance Computing and Programming Event
"OpenACC and GPU Handson workshop"
Presented by Presented by NVIDIA instructor Bob Crovella
Wednesday, May 25, 2016, 8:30 am
Stony Brook University
NVIDIA and the Institute for Advanced Computational Science (IACS) at Stony Brook University are pleased to be organizing a 2day High Performance Computing and Programming event. Presented by NVIDIA instructor Bob Crovella, the workshop will introduce programming techniques using OpenACC and will include topics such as optimization and profiling methods for GPU programming.
Nuclear Physics Seminar
"Exploring the Neutron Spin Structure"
Presented by Matt Posik, Temple University
Tuesday, May 24, 2016, 11 am
Small Seminar Room, Bldg. 510
Hosted by: 'Oleg Eyser'
Jefferson Lab experiment E06014, performed in Hall A, made measurements of the doublespin asymmetries and absolute cross sections in both the DIS and resonance regions by scattering longitudinally polarized electrons at beam energies of 4.74 and 5.89 GeV from a longitudinally and transversely polarized 3He target. Through these measurements various aspects of the neutron spin structure were investigated. The g2 nucleon spindependent structure function contains information beyond the simple parton model description of the nucleon. It provides insight into quarkgluon correlations and a path to access the confining local color force a struck quark experiences just as it is hit by the virtual photon due to the remnant diquark. The quantity d2, a measure of this local color force, has its information encoded in an x2 weighted integral of a linear combination of spin structure functions g1 and g2 and thus is dominated by the valencequark region at large momentum fraction x. To date, theoretical calculations and experimental measurements of the neutron d2 differ by about two standard deviations. Therefore E06014 made a precision measurement of this quantity. The polarized quark distributions were also investigated through measurements of the virtual photonnucleon asymmetry A1^n, the structure function ratio g1/F1, and quark ratio (delta d+delta d_bar)/(d+d_bar). The E06014 results for the spin structure functions (g1,g2) on 3He, dn2, An1, (delta d+delta d_bar)/(d+d_bar), and our extractions of the neutron color electric and magnetic forces will be presented.
High Performance Computing and Programming
"OpenACC and GPU Handson workshop"
Presented by Presented by NVIDIA instructor Bob Crovella
Tuesday, May 24, 2016, 8:30 am
Stony Brook University
NVIDIA and the Institute for Advanced Computational Science (IACS) at Stony Brook University are pleased to be organizing a 2day High Performance Computing and Programming event. Presented by NVIDIA instructor Bob Crovella, the workshop will introduce programming techniques using OpenACC and will include topics such as optimization and profiling methods for GPU programming.
Nuclear Theory/RIKEN Seminar
"The jet quenching parameter qhat, and its relation to the TMDPDF"
Presented by Abhijit Majumdar, Wayne State University
Friday, May 20, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: '''Soeren Schlichting'''
Based on prior work by the JET collaboration, the importance of the factorization and scale evolution of the jet quenching parameter qhat will be outlined. This will turn out to be important for both phenomenological extractions of qhat as well as for first principle determinations on the lattice. I will argue that for jets at RHIC and LHC, qhat does not lie within the range of Bjoerkenx where small x effects would be considered to be dominant. Given this situation, qhat will be found to be an integral over an operator product separated in both lightcone and transverse distance, but somewhat different from a ``traditional'' TMDPDF. This new distribution will be studied at NexttoLeading Order and the fate of nonstandard divergences discussed.
Particle Physics Seminar
"Searches for New Physics in boosted diboson topologies at ATLAS"
Presented by Carmacho Toro, University of Chicago
Thursday, May 19, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: 'Michael Begel'
The large increase in collision energy that the LHC reached in Run 2 provides an unprecedented opportunity to search for new physics beyond the Standard Model (SM). Various extensions of the SM predict the existence of heavy resonances at the TeV scale, which couple predominantly to the Higgs and electroweak gauge bosons. At high resonance masses the hadronic decay products of these energetic bosons tend to be highly collimated and the usual identification techniques fail to disentangle the decay products of our bosons. In this seminar I will describe the jetsubstructure techniques explored by ATLAS analyses and present the results of the ATLAS searches using Run2 data.
RIKEN Lunch Seminar
"KosterlitzThouless transition and chiral rotation in external electromagnetic field"
Presented by Gaoqing Cao, Fudan University
Thursday, May 19, 2016, 12:30 pm
Building 510, Room 2160
Hosted by: ''Daniel Pitonyak''
In 2+1 dimensional system, the most important phase transition should be of the KosterlitzThouless (KT) type. We determined the KT transition temperature T_KT as well as the mass melting temperature T^* as a function of the magnetic field. It is found that the pseudogap domain T_KT < T < T^* is enlarged with increasing strength of the magnetic field. The influence of a chiral imbalanceμ_5 was also studied. We found that even a constant axial chemical potential μ_5 can lead to inverse magnetic catalysis of the KT transition temperature in 2+1 dimensions. This is actually the de Haas—van Alphen oscillation. Furthermore, we studied the QCD vacuum structure under the influence of an electromagnetic field with a nonzero second Lorentz invariant I_2=E·B. We showed that the presence of I_2 can induce neutral pion (π_0) condensation in the QCD vacuum through the electromagnetic triangle anomaly. Within the frameworks of chiral perturbation theory at leading smallmomenta expansion as well as the Nambu—JonaLasinio model at leading 1/Nc expansion, a universal dependence of the π_0 condensate on I_2 was found. The stability of the π_0condensed vacuum is also discussed.
HET/RIKEN Seminar
"Higgs Pair Production in Extensions of the Standard Model"
Presented by Ramona Groeber, Roma Tre
Wednesday, May 18, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: 'Pier Paolo Giardino'
Higgs pair production is not only interesting as a probe of the trilinear Higgs selfcoupling, but beyond the Standard Model physics can influence the Higgs pair production cross section in many different ways, for example by new couplings, new loop particles or new resonances. In this talk, I will address the question whether we could see for the first time deviations from the Standard Model in Higgs pair production assuming that no deviations were seen before. Furthermore, for certain models I will show how higher order corrections influence the cross section.
CondensedMatter Physics & Materials Science Seminar
"Equilibrium States and Dynamics of Spin Assemblies in Magnetic Thin Films, Heterostructures and Nanostructured Entities"
Presented by Ramesh B. Budhani, Indian Institute of Technology Kanpur
Tuesday, May 17, 2016, 11 am
Building 480, Conference Room
Hosted by: 'Lijun Wu'
The orientation of spin assemblies in ferromagnetic thin films and nanostructures can take a variety of shapes depending on the relative strength of factors contributing to their magnetic free energy. These factors are derived from the direct quantum mechanical exchange between the electronic spins or those mediated by impurities, and those associated with the size, shape, crystallographic structure, strain, dipolar interactions and external fields. Here we present three cases where the orientational dynamics has been studied as functions of temperature, magnetic field strength and the elapsed time after acquiring a particular configuration. These studies are based on magnetic force microscopy and bulk magnetometry measurements on strain epitaxial films of La0.67Ca0.33MnO3, and lithographically patterned submicron size ring assemblies of permalloy and Co/Pd multilayers, which also form artificial spin ices. Towards the end of this lecture we will discuss interface driven magnetic and electronic phenomena in magnetic thin films.
CondensedMatter Physics & Materials Science Seminar
"Dirac Materials"
Presented by Alexander Balatsky, Los Alamos National Laboratory
Monday, May 16, 2016, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)
Hosted by: 'Peter D. Johnson'
Discoveries of superfluid phases in 3He, high Tc superconductors, graphene and topological insulators have brought into focus materials where quasiparticles are described by same Dirac equation that governs behavior of relativistic particles. I will discuss how this class of materials, called Dirac materials, exhibits unusual universal features seen in numerous realizations: Klein tunneling, chiral symmetries and impurity resonances. Goal of this talk is to explore these similarities and discuss the unique role of symmetries that protect Dirac spectrum and possible routes to generate gaps due to many body instabilities. We will also discuss ongoing investigation of the symmetries of Dirac materials, quantum imaging, and means to control their properties. At the end we will propose to use modern tools to design artificial Dirac Materials. One example would be the design Bosonic Dirac materials that host bosonic Dirac excitations, something that would not be possible in particle physics.
Nuclear Theory/RIKEN Seminar
"Evolution of the jet opening angle distribution in holographic plasma"
Presented by Andrei Sadofyev, MIT
Friday, May 13, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Soeren Schlichting''
Energetic jets are particularly interesting probes of QGP created in heavy ion collisions. Recently a lot of progress was made in attempting to describe the jet evolution in holography. In this talk I'll present an application of a simple dual model to study the jet substructure starting with energy and angle distributions from pQCD. In particular I will show that there are two competing effects: (1) each individual jet widens as it propagates through plasma; (2) the final jet opening angle distribution becomes narrower since wider jets lose more energy and less likely to survive. So, the mean opening angle for jets with a given energy can easily shift toward smaller angles, even while every jet in the ensemble broadens.
Particle Physics Seminar
"Muon antineutrino oscillations at T2K"
Presented by Jordan Myslik, University of Victoria
Thursday, May 12, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: 'Xin Qian'
The T2K ("Tokai to Kamioka") experiment is a longbaseline neutrino oscillation experiment in Japan. A beam of muon neutrinos or muon antineutrinos is produced at the Japan Proton Accelerator Research Complex (JPARC) in Tokai. The unoscillated neutrino flux is measured by the near detector complex 280 m from the proton target, and the oscillated neutrino flux is measured by the far detector, SuperKamiokande, 295 km away. Using a beam of muon neutrinos, T2K has performed precise measurements of muon neutrino disappearance, and discovered muon neutrino to electron neutrino oscillation by measuring electron neutrino appearance. Since the summer of 2014, T2K has been taking data using a beam of muon antineutrinos, and has released the results of both a muon antineutrino disappearance analysis and an electron antineutrino appearance analysis, both using antineutrino beam data up to the summer of 2015. This talk will discuss these analyses, going into detail about the role played by the near detector, and looking at future directions.
RIKEN Lunch Seminar
"The Functional Renormalization Group Method and Delayed Magnetic Catalysis"
Presented by Stefan Rechenberger, University of Darmstadt
Thursday, May 12, 2016, 12:30 pm
Building 510, Room 2160
Hosted by: ''Daniel Pitonyak''
This talk will start with a very general introduction to the Functional Renormalization Group method, a powerful nonperturbative tool which can be applied to various problems. The second part of the talk will demonstrate this by discussing the influence of an external magnetic field on the chiral phase transition in the theory of strong interaction. The Functional Renormalization Group analysis shows that, driven by gluon dynamics, the chiral critical temperature decreases for small values of the magnetic field. For large values of the external field, however, the phase transition temperature increases.
HET/RIKEN Seminar
"Axions and Topology"
Presented by Simon Mages, Forschungszentrum Juelich
Wednesday, May 11, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Tomomi Ishikawa''
This talk will be centered around the calculation of the high temperature topological susceptibility in QCD. It will provide some background on our motivation from cosmology and particle physics, which is the dependence of axion physics on nonperturbative QCD. I will show our recent results on the quenched high temperature topological susceptibility and discuss difficulties with this conventional approach, which render dynamical studies unfeasible. I will also present our new approach based on formulating QCD on a nonorientable manifold, which is a promising candidate to solve issues related to topological freezing and the divergence of autocorrelations when approaching the continuum limit.
Nuclear Theory/RIKEN seminar
"Fluid dynamics for the anisotropically expanding quarkgluon plasma"
Presented by Dennis Bazow, The Ohio State University
Friday, May 6, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Soeren Schlichting''
Local momentum anisotropies become large in the early stages of the quarkgluon plasma created in relativistic heavyion collisions, due to the extreme difference in the longitudinal and transverse expansion rates. In such situations, fluid dynamics derived from an expansion around an isotropic local equilibrium state is bound to break down. Instead, we subsume the slowest nonhydrodynamic degree of freedom (associated with the deviation from momentum isotropy) at leading order defining a local anisoptropic quasiequilibrium state, thereby treating the longitudinal/transverse pressure anisotropy nonperturbatively. Perturbative transport equations are then derived to deal with the remaining residual momentum anisotropies creating a complete transient effective theory called viscous anisotropic hydrodynamics. This approach has been shown to dramatically outperform viscous hydrodynamics in several simplified situations for which exact solutions exits but which share with realistic expansion scenarios the problem of large dissipative currents. We will discuss the present status of applying viscous anisotropic hydrodynamics to the phenomenological description of the quarkgluon plasma in realistic expansion scenarios.
Particle Physics Seminar
"Probing the Nature of Neutrinos with Double Beta Decay"
Presented by Liang Yang, University of Illinois at UrbanaChampaign
Thursday, May 5, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: 'Xin Qian'
Understanding fundamental properties of neutrinos is of compelling interest to the nuclear and particle physics community. The discovery of neutrino oscillations is one of our first hints of physics beyond the Standard Model. Searching for neutrinoless double decay can provide key insights into the neutrino mass generation mechanism and put stringent constraints on the absolute neutrino mass scale. Such a rare decay, if exists, would signify the Majorana nature of neutrinos and the nonconservation of lepton number. In the past decade, large ultralow background liquid xenon detectors have emerged as a promising technology that can push the neutrinoless double beta decay search to unprecedented sensitivity. In this talk I will describe recent results and prospects of current generation experiment EXO200, as well as the R&D program for future tonne scale detector nEXO.
RIKEN Lunch Seminar
"Vorticity in heavyion collisions and cold atoms"
Presented by XuGuang Huang, Fudan University
Thursday, May 5, 2016, 12:30 pm
Building 510, Room 2160
Hosted by: ''Daniel Pitonyak''
Vorticity describes the local rotation of the fluid. I will talk about our recent study of the eventbyevent generation of flow vorticity in heavyion collisions. Several special properties of the vorticity in heavyion collisions will be discussed, e.g., the impact parameter dependence, the collision energy dependence, the spatial distribution, the eventbyevent fluctuation of the magnitude and azimuthal direction. Vorticity can drive vector and axial current in chiral quarkgluon plasma via the chiral vortical effect. I will discuss the collective gapless mode, the chiral vortical wave, emerging from CVE and its experimental implications in heavyion collisions. Finally, I will consider the rotating trapped cold atomic gases and show that when there is a Weyl spinorbit coupling such cold atomic gases provide a desktop simulator of the chiral magnetic effect and chiral separation effect.
Physics Colloquium
"eRHIC Machine Design"
Presented by Thomas Roser, BNL
Tuesday, May 3, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: 'Robert Pisarski'
With the addition of a 20 GeV polarized electron accelerator to the existing Brookhaven Relativistic Heavy Ion Collider (RHIC), the world?s only high energy heavy ion and polarized proton collider, a future eRHIC facility will be able to produce polarized electronnucleon collisions at centerofmass energies of up to 145 GeV and cover the whole science case as outlined in the ElectronIon Collider White Paper and endorsed by the 2015 Nuclear Physics Long Range Plan with high luminosity. The presentation will describe the eRHIC design concepts and recent efforts to reduce the technical risks of the project.
High Tc Superconductor Seminar
"Cooperlike paring and energy gap induced by ion electronic polarizability"
Presented by Yizhak Yacoby, Racah Institute of Physics, Hebrew University, Israel
Monday, May 2, 2016, 1:30 pm
Bldg. 734, ISB Conference Room 201 (upstairs)
Hosted by: ''Ron Pindak and Ivan Bozovic''
We propose a model of Cooperlike pairing induced by the large ion polarizabilities of O2 in Bismutates and Cuprates and As3 and Se2 in the iron pnictides*. We show that the electrical potential field induced by a charge carrier contains in its vicinity pockets of negative potential causing charge carriers to attract each other. Using this model we calculate the approximate pairing and gap energies showing they are compatible with the gap energies measured in highTc superconductors. Furthermore we show that the isotope effect, coherence length, and the gap energy dependence on doping are consistent with those observed in highTc systems. * Work done in collaboration with Yakov Girshberg
Nuclear Theory/RIKEN Seminar
"Going with the flow: sign problem, Lefschetz thimbles and beyond"
Presented by Gokce Basar, University of Maryland
Friday, April 29, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: '''Soeren Schlichting'''
Monte Carlo method, a robust way of studying field theories and many body systems, suffers from the sign problem when the action is complex. This includes an important set of problems such as most field theories, including QCD, and strong correlated electronic systems at finite density, as well as computation of real time quantities like transport coefficients. I will show that lifting the path integration to a complex manifold provides a way to ameliorate the sign problem, and introduce a new algorithm for carrying on such a computation. I will give some quantum mechanical examples with severe sign problems, including finite density of fermions and real time observables where Monte Carlo simulations can be profitably performed by this method. Finally I will discuss the 3+1d Bose gas with nonzero chemical potential.
Particle Physics Seminar
"Higgs' invisible branching fraction at the LHC"
Presented by Tae Min Hong, University of Pennsylvania
Thursday, April 28, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: 'Michael Begel'
Does the Higgs have a large invisible branching fraction? Two approaches are presented. The first is an indirect constraint of the invisible branching fraction using precision Higgs couplings measurements. The second is a direct search of invisible decays. In particular, I will discuss in detail two of ATLAS's results: the H > WW in VBF, which is one of the strongest inputs for the couplings and the evidence for VBF Higgs production, and the H > invisible in VBF, which gives the strongest direct limit. Comparisons with CMS's results are made.
RIKEN Lunch Seminar
"Solving QCD2"
Presented by Alexei Tsvelik, BNL
Thursday, April 28, 2016, 12:30 pm
Building 510, Room 2160
Hosted by: 'Daniel Pitonyak'
We study a (1+1)dimensional version of the famous NambuJonaLasinio model of Quantum Chromodynamics (QCD2) both at zero and finite chemical potential. We use non perturbative techniques (nonAbelian bosonization and Truncated Conformal Space Approach). At zero chemical potential we describe a formation of fermion threequark (nucleons and ?baryons) and boson (twoquark mesons, sixquark deuterons) bound states and also a formation of a topo logically nontrivial phase. When the chemical potential exceeds the critical value, the model has a rich phase diagram which includes phases with density wave and superfluid quasilongrange (QLR) order and also a phase of a baryon TomonagaLuttinger liquid (strange metal). The QLR order results as a condensation of scalar mesons (the density wave) or sixquark bound states (deuterons).
HET/RIKEN Seminar
"Heavy Higgs Resonance Dip"
Presented by Sunghoon Jung, SLAC
Wednesday, April 27, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Cen Zhang''
We discuss overlooked resonance shapes of heavy Higgs bosons that arise from the resonancecontinuum interference with a complex phase. They include pure resonance dips and nothingness. We derive conditions under which they are produced and we modify narrow width approximation suitable for them. We then discuss how MSSM heavy Higgs searches at the LHC can be challenged and changed.
Physics Colloquium
"Neutrino Physics and Mass from Cosmology"
Presented by Marilena Loverde, Stony Brook University
Tuesday, April 26, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: 'Robert Pisarski'
Cosmic background neutrinos are nearly as abundant as cosmic microwave background photons, but their mass, which determines the strength of their gravitational clustering, is unknown. Neutrino oscillation data gives a strict lower limit on neutrino mass, while cosmological datasets provide the most stringent upper limit. Even if the neutrino masses are the minimum required by oscillation data, their gravitational effects on structure formation will nevertheless be detectable in — and in fact required to explain — data within the next decade. I will discuss the physical effects of the cosmic neutrino background on structure formation and present a new signature that may be used to measure neutrino mass with large galaxy surveys.
Center for Functional Nanomaterials Seminar
"Disordered water phases from ambient to ultrahigh pressure"
Presented by Roberto Car, Princeton University
Tuesday, April 26, 2016, 11 am
CFN, Bldg. 735, 2nd Fl. Seminar Room
Hosted by: 'Deyu Lu'
Center for Functional Nanomaterials Special Seminar Disordered water phases from ambient to ultrahigh pressure Roberto Car Princeton University Tuesday, April 26, 2016 11:00 a.m. CFN, Bldg. 735, 2nd floor Seminar Room The unusual properties of water, including the thermodynamic anomalies of the liquid, the existence of more than one amorphous ice form, and the abnormal mobilities of the water ions, derive from the tetrahedral network of hydrogen bonds that hold the molecules together. Under applied pressure the topology of the network changes but local tetrahedrality is preserved as the system explores a variety of different phases until at extreme pressure the molecules dissociate into ions and the hydrogen bonds collapse. Modern abinitio simulations provide a unifying picture of these processes. In this talk, I will review recent progress in these studies stressing connections between theory, simulation, and experiment. Bio Roberto Car of Princeton University is Ralph W. Dornte professor for chemistry with a simultaneous appointment at the Material Sciences Institute of the university. He is a professor in the Theory Department, of the Fritz Haber Institute of the Max Planck Society. His research focus is theory and numerical simulation (classical and quantum) of condensed and molecular systems. He studied physics and attained a doctorate in 1971 in nuclear technology at the Politecnico di Milano. After being professor for physics at SISSA in Trieste (19841991), and at University of Geneva (19911999) he joined Princeton University in 1999. In 2007, a birthday symposium was held at ICTP. He received the Aneesur Rahman prize in computational physics. The Aneesur Rahman Prize is the highest honor given by the American Physical Society for work in computational physics.
CAD Accelerator Physics Seminar
Presented by Malek Haj Tahar, BNL
Friday, April 22, 2016, 4 pm
Large Conference Room, Bldg. 911B, Rm. A202
"The problem of nuclear waste continues to raise lots of concerns of whether the nuclear power should continue when the issue of how to deal with its waste has not yet been resolved. After reviewing the history of the nuclear waste problem in the United States of America and other countries, the question of how to remediate this problem is tackled and several options discussed. The focus is on the Accelerator Driven System option, a hybrid technique combining a particle accelerator with a subcritical core. The scope includes technical considerations from the proton accelerator and up to the reactor core."
Particle Physics Seminar
"New constraints on cosmic inflation from the Keck Array"
Presented by Chris Sheehy, University of Chicago
Thursday, April 21, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: 'Anze Slosar'
The Keck Array, part of the BICEP/Keck program of small aperture cosmic microwave background (CMB) telescopes, is currently taking data at the South Pole in Antarctica. The goal of the BICEP/Keck program is to detect the Bmode pattern in the CMB's polarized anisotropy that would be a signature of cosmic inflation, or, barring a detection, to set upper limits that rule out some of the most favored theoretical scenarios. Previous results from BICEP2 and the Keck Array that detected Bmodes at high significance consisted of data taken only at 150 GHz, and which could therefore not conclusively distinguish between a cosmological vs. galactic origin for the signal. A subsequent joint analysis with the Planck satellite collaboration that invoked their comparatively noisy but multifrequency maps revealed a large component of the signal to be from polarized thermal emission of galactic dust. In this talk, I will present the results from the first year of observations with Keck's new 95 GHz receivers. These results set the most stringent limits on cosmic inflation to date and mark the point at which CMB polarization now constrains inflation better than any other data set.
RIKEN Lunch Seminar
"Color fluctuation phenomena in high energy hadron & photonA collisions"
Presented by Mark Strikman, Penn State University
Thursday, April 21, 2016, 12:30 pm
Building 510, Room 2160
Hosted by: ''Daniel Pitonyak''
Compositeness of the bound states and the Lorentz slowing down of high energy interactions in QED and QCD lead to emergence of new coherent phenomena. We focus on the phenomena related to the fluctuations of the strength of interaction (color fluctuations phenomena). First we consider gross violations of the Glauber model for centrality dependence of production of the leading jets in pA scattering predicted earlier within QCD and recent evidence for this phenomenon from the studies of hard pA collisions at the LHC and dAu collisions at RHIC. Color fluctuations also explain a large suppression of the cross section of coherent vector meson photoproduction as compared to the Glauber model observed recently in the ultraperipheral collisions at LHC. We outline perspectives of future studies of the color fluctuation phenomenon in ultraperipheral heavy ion collisions at the LHC and electron  nucleus colliders.
Environmental & Climate Sciences Department Seminar
"Improved Tandem Measurement Techniques for Gas Phase Nanoparticle Analysis"
Presented by Vivek Rawat, University of Minnesota
Wednesday, April 20, 2016, 11 am
Conference Room, Bldg 815E
Hosted by: 'Jian Wang'
Nonspherical, chemically inhomogeneous nanoparticles are encountered in a number of natural and engineered environments, including combustion systems, reactors used in gasphase materials synthesis, and in ambient air. To better characterize these complex nanoparticles, tandem measurement techniques are well suited, in which analytes are characterized by two orthogonal properties (e.g. size and mass). Tandem measurement techniques have been applied in a number of situations; however, there are still a considerable number of fundamental developments needed to advance these approaches. Specifically, new instrument combinations (with existing instruments) and appropriate data inversion routines need to be developed to determine combined twodimensional masssize distribution functions, pure mass distribution and for mobilitymass analysis for sub 2nm clusters (ions). With this motivation, we first develop and apply a data inversion routine to determine the number based sizemass distribution function (two dimensional distribution) from tandem differential mobility analyzeraerosol particle mass analyzer (DMAAPM) measurements, while correcting for multiple charging, instrument transfer functions and other system efficiencies. This two dimensional distribution can be used to calculate the number based size distribution or the mass based size distribution. We employ this technique to analyze various spherical and nonspherical nanoparticles and examine the validity of this approach by comparing the calculated size distribution functions and mass concentrations with direct measurements of these quantities. In a second study, we utilize a transversal modulation ion mobility spectrometer (TMIMS) coupled with a mass spectrometer (MS) to study vapor dopant induced mobility shifts of sub 2 nm ion clusters. Isopropanol vapor is introduced into the TMIMS, shifting the mobilities of ions to varying extents depending on ion surface chemistry, which provides an improved separa
Physics Colloquium
"The nature of the composite fermion in quantum Hall liquids"
Presented by Dam Thanh Son, University of Chicago
Tuesday, April 19, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: 'Robert Pisarski'
The quantum Hall liquids are some of the most nontrivial strongly interacting states of matter. Experiments have established the existence of the composite fermion as an effective degree of freedom of quantum Hall systems near half filling. A longstanding problem of existing theories of the composite fermion is the lack of particlehole symmetry of the lowest Landau level. I will describe how the particlehole symmetry took a central role in recent theoretical discussions of the fractional quantum Hall effect; in particular, how a recent synthesis, motivated by the physics of graphene and topological insulators, has lead to a new understanding of the lowenergy quasiparticle of the halffilled Landau level. According to the new picture, the composite fermion is a Dirac particle, with a gauge but nonChernSimons interaction. Distinctive consequences of the new proposal are outlined.
Nuclear Theory/RIKEN seminar
"Vorticular fluid and Lambda Polarization in Highenergy Heavyion Collisions"
Presented by XinNian Wang, LBNL/CCNU
Friday, April 15, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Soeren Schlichting''
The strongly coupled quarkgluon plasma created in highenergy heavyion collisions has rich vortical structures that are caused by global total orbital angular momentum and transverse evolution of longitudinal flow. Fermions (quarks in sQGP phase and baryons in the hadronic phase) in such a vorticular fluid are naturally polarized due to spinorbital. I will discuss both local and global quark polarization and how one can use the lambda polarization in the final state to study the vortical structure and constrain the transport properties of sQGP.
Particle Physics Seminar
"Nuclear reactor antineutrinos, hard to detect but with a traceable lineage."
Presented by Alejandro Sonzogni, BNL
Thursday, April 14, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: 'Xin Qian'
The antineutrino spectrum from nuclear reactors can be calculated using the socalled "summation method", which requires precise knowledge of the fission yield and decay properties of the about 1000 radionuclides produced in a reactor following the fission of the actinide fuel. Alternatively, the antineutrino spectra can also be calculated using the "conversion method", which relies on precisely measured electron spectra. We have recently updated both decay and fission data that enabled us to a) identify the nuclides that contributes the most at different energy regions, b) derive a systematic of the IBD cross section integrated spectra as function of Z and A, similar to that of betadelayed neutrons, c) asses if an excess of antineutrinos observed at around 5.5 MeV can be discerned using nuclear data.
Center for Functional Nanomaterials Seminar
"Sub50 fs Photophysics and Photochemistry of Transition Metal Complexes and Polyhalomethanes"
Presented by Sergey Mikhailovich Matveev, Bowling Green State University
Monday, April 11, 2016, 1:30 pm
CFN, Bldg. 735, 1st floor conf. rm. A
Hosted by: 'Mircea Cotlet'
Lowest energy electronic excited states (LEES) in transition metal complexes are the states most relevant for practical photophysical and photochemical processes. We investigated relaxation dynamic of two systems – copper chloride dianion with strong JahnTeller effect and hexabromoiridate dianion with spinspin coupling, utilizing 2000 nm nearIR femtosecond (100 fs) pumpprobe spectroscopy. In both systems, the Franc Condon excited states of the transition metal complexes undergo internal conversion to the ground electronic states, but with significantly different lifetimes (55 fs and 360 ps, respectively), despite the fact that the metalcentered states are separated by the same energy gap (~5000 wavenumbers) from the respective ground state. This difference is explained by presence of a conical intersection between the first excited electronic and the ground states in the Cu(II) system due to strong JahnTeller linear distortion whereas the involved potential energy surfaces for the Ir(IV) complex are nested directly one above another. Another project under consideration is the ultrafast mechanisms of polyhalomethanes on the example of diiodomethane. This molecule has a tractable number of degrees of freedom, and, therefore, has served in literature as a model system for bond dissociation processes in both gas and condensed phases. In this work we implemented the stateoftheart ultrafast (~35 fs) transient absorption experiment (supported by the most accurate multireference quantum chemical methods) to understand the UV photodissociation mechanism of methylene iodide molecules. We discovered previously unsuspected photochemical pathway in the UV photochemistry of methylene iodide, in which electronically excited molecules, rather than simply dissociate, undergo direct ~50fs isomerization through a conical intersection into isomeric species. Host: Mircea Cotlet
Particle Physics Seminar
"Dark Matter Search Results from PICO2L"
Presented by Chanpreet Amole, Queen's University, SNOLAB
Thursday, April 7, 2016, 10 am
Small Seminar Room, Bldg. 510
Hosted by: 'Xin Qian'
New data are reported from a second run of the 2liter PICO2L C3F8 bubble chamber with a total exposure of 129 kgdays at a thermodynamic threshold energy of 3.3 keV. These data show that measures taken to control particulate contamination in the superheated fluid resulted in the absence of the anomalous background events observed in the first run of this bubble chamber. One single nuclearrecoil event was observed in the data, consistent both with the predicted background rate from neutrons and with the observed rate of unambiguous multiplebubble neutron scattering events. The chamber exhibits the same excellent electronrecoil and alpha decay rejection as was previously reported. These data provide the most stringent direct detection constraints on WIMP proton spindependent scattering to date for WIMP masses < 50 GeV/c2.
'Science on Tap'
"A Conversation With Paul Sorensen"
Presented by Paul Sorensen, Brookhaven Lab
Tuesday, April 5, 2016, 7 pm
Stony Brook Yacht Club
Hosted by: ''Alan Alda Center for Communicating Science''
Paul Sorensen recreates the birth of the universe, smashing the nuclei of gold atoms together with such extreme violence that they melt into a cosmic soup that hasn't existed since the universe was a microsecond old. In conversation with Stony Brook University's journalism professor, Steven Reiner, Sorensen will bring to vivid life the epic endeavor to create in Brookhaven National Laboratory's atom smasher minute specks of the hottest matter ever made on Earth, and tell us what these fleeting fireballs may reveal about the origin of everything, including ourselves.
Physics Colloquium
"Hunting for WIMPs in Panda Land"
Presented by Xiangdong Ji, University of Maryland
Tuesday, April 5, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: ''''Robert Pisarski''''
Weakly interacting massive particles (WIMPs), with properties similar to those of a heavy neutrino, have been a leading candidate for the 27% dark matter in the Universe. Direct detection experiments by detecting the nuclear recoils from elastic scattering of WIMPs with atomic nuclei have made huge strides in the last decade, improving the sensitivity by some five orders of magnitude. In this talk, I will describe the results from an adventure of searching for WIMPs with the PandaX, currently the most sensitive running liquid xenon dark matter detector, in the world's deep underground lab in the high mountains, western China.
Nuclear Theory/RIKEN seminar
"Studying Nucleons in Soliton Models"
Presented by Song Shu, Stonybrook University
Friday, April 1, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Soeren Schlichting''
Both chiral solitons and confined solitons are discussed at finite temperatures and densities in effective models. Based on the solitons the nucleon properties are studied in thermal medium. The nucleon mass in medium is carefully calculated. It is showed that the chiral solitons could even survive after the chiral phase transition, while confined solitons collapse after the system is deconfined.
Particle Physics Seminar
"Milicharge: A Proposal"
Presented by Ben Kaplan, New York University
Thursday, March 31, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Michael Begel''
I will present the status of the MilliQan experiment, a millicharged particle detector we propose to install at LHC P5. The experiment would be commissioned during the next LHC shutdown in a service tunnel ~30m above the CMS interaction point, behind ~15m of rock. I will present the theoretical motivation for building the detector, its proposed experimental design, and the expected sensitivity to millicharged particles.
RIKEN Lunch Seminar
"Sphalerons Far From Equilibrium and Associated Phenomena"
Presented by Mark Mace, Stony Brook University
Thursday, March 31, 2016, 12:30 pm
Building 510 Room 2160
Hosted by: 'Daniel Pitonyak'
In this talk, I will present a first computation of sphalerons in the glasma; the highly occupied, weakly coupled gluon dominated preequilibrium matter created at early times after an ultrarelativistic heavy ion collisions. The sphaleron transition is a well known ingredient in the generation of anomalous vector current from a strong external magnetic field, the socalled Chiral Magnetic Effect. We perform classicalstatistical realtime lattice simulations to study the dynamics of these topological transitions; simplifying our description by employing SU(2) gauge fields and neglecting the longitudinal expansion for this first study. I will show that the nonequilibrium sphaleron transition rate is time dependent and nonMarkovian, in addition to being dominant in comparison to the thermal equilibrium sphaleron transition rate. In addition, we can measure the scaling and separation of physical scales in analogy to those from thermal equilibrium, in order to parameterize this rate and understand the approach to equilibrium. I will then demonstrate that it is the magnetic screening length, which we extract nonperturbatively, that controls this rate. Additionally, I will briefly mention studies of related anomalous transport effects that we plan on studying using this first principles classicalstatistical realtime lattice technology.
CondensedMatter Physics & Materials Science Seminar
"Topological Insulators and Dirac Semimetals  Recent Progress in New Materials"
Presented by Robert J. Cava, Princeton University
Thursday, March 31, 2016, 10 am
Large Seminar Room, Bldg. 510
Hosted by: ''Peter D. Johnson''
"New materials give new properties" describes the goal of our solid state chemistry research program. This goal would be much easier to attain if there was a reliable way to predict the stability of an unknown nonmolecular solid, then predict what its properties would be, then make it as a real material and then finally test it, but unfortunately that is not the case; establishing such a process is the grand challenge in contemporary solid state chemistry, and so we have to operate differently. Our discussions with experimental and theoretical physicists teach us about current issues in the electronic and magnetic properties of matter, and our chemistry background teaches us how to think about crystal structures and bonding; our work is about trying to put these two cultures together to find new materials. In this talk I will describe some of our recent results in Topological Insulators and Dirac and Weyl Semimetals.
Physics Colloquium
"QuarkGluon Plasma: An Old and New Phase of Quantum Matter"
Presented by Jinfeng Liao, Indiana University
Tuesday, March 29, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
The use of fire was instrumental for human civilization. Early conception of varied phases of matter as well as transitions among them, perhaps developed from e.g. burning wood and heating water. Those ancient pursuits continue into the modern quest for understanding the structure of matter under extreme conditions: what's the phase of matter when heated to unprecedented temperature? The answer to this question relies upon our understanding of the strong nuclear force, which is described by quantum chromodynamics (QCD). First principle calculations of QCD predict that the normal nuclear matter, when heated to be hot enough, will change into a new phase of matter called the quarkgluon plasma (QGP). In fact, the QGP was an old phase of matter that occupied the early universe shortly after the Big Bang. Today, such primordial droplets of QGP can be recreated repeatedly and measured precisely in relativistic heavy ion collisions (often called the Little Bangs). Remarkable discoveries have been made at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) that together reveal the QGP as a nearly perfect quantum liquid with superior opaqueness. We will discuss a number of novel properties of QGP. In particular we will highlight the recent progress on how certain unusual transport phenomena stemming from microscopic chiral anomaly, which is intrinsically quantum mechanical, could manifest themselves in the macroscopic QGP fluid. A very brief survey will be given on the theoretical developments, the experimental search in heavy ion collisions, as well as the recent exciting progress of such physics in Dirac and Weyl semimetals.
CondensedMatter Physics & Materials Science Seminar
"Phase transitions in strongly correlated systems from diagrammatic multiscale methods"
Presented by Andrey Antipov, University of Michigan
Thursday, March 24, 2016, 1:30 pm
Bldg. 734, ISB Conf. Rm. 201 (upstairs)
Hosted by: ''Alexei Tsvelik''
The dynamical mean field theory (DMFT) has become the standard tool in describing strongly correlated electron materials. While it captures the quantum dynamics of local fields, it neglects spatial correlations. To describe e.g. antiferromagnetism, unconventional superconductivity or frustration a proper treatment of nonlocal correlations is necessary. Diagrammatic multiscale approaches offer an elegant option to accomplish this: the difficult correlated part of the system is solved using a nonperturbative manybody method, whereas 'easier', 'weakly correlated' parts of the problem are tackled using a secondary perturbative scheme. Here we employ such a method, the dual fermion approach, to problems of charge and spin ordering in FalicovKimball and Hubbard models by constructing a systematic diagrammatic extension on top of DMFT. Near the critical point model we study the interplay between charge and spin excitations and longrange fluctuations. We show that such multiscale approach is indeed capable of capturing the non meanfield nature of the critical point of the lattice model and correctly describes the transition to meanfield like behavior as the number of spatial dimensions increases. Our numerical method is available as a freely distributed opensource code.
Special RIKEN/HET Seminar
"Axion Phenomenology from Unquenched Lattice QCD"
Presented by Guido Martinelli, Rome University
Thursday, March 24, 2016, 11 am
Large Seminar Room, Bldg. 510
Hosted by: '''Hiroshi Oki'''
We investigate the topological properties of Nf = 2 + 1 QCD with physical quark masses, both at zero and finite temperature. At zero temperature both finite size and finite cutoff effects have been studied by comparing the continuum extrapolated results for the topological susceptibility χ with the predictions from chiral perturbation theory. At finite temperature, we explore a region going from Tc up to around 4Tc, where continuum extrapolated results for the topological susceptibility and for the fourth moment of the topological charge distribution are obtained. While the fourth moment converges to the dilute instanton gas prediction the topological susceptibility differs strongly both in the size and in the temperature dependence. This results in a shift of the axion dark matter window of almost one order of magnitude with respect to the instanton computation.
Physics Colloquium
"Flavor Physics for Non Experts : (A Theory) Overview"
Presented by Guido Martinelli, Rome University
Tuesday, March 22, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
The status of the Unitarity Triangle including the most recent results from LHC, will be presented. Different possibilities for detecting, in the quark sector, signals of physics beyond the Standard Model will be considered. The conclusion is that, even allowing for general New Physics loop contributions, the generalized Unitarity Triangle must be very close to the Standard Model one. Together with direct searches of new particles at LHC, this result strongly constraints models of New Physics.
CondensedMatter Physics & Materials Science Seminar
"SU(N) symmetric tensor network simulations of strongly correlated quantum manybody systems"
Presented by Andreas Weichselbaum, Ludwig Maximilians University
Tuesday, March 22, 2016, 1:30 pm
Small Seminar Room, Bldg. 510
Hosted by: ''Alexei Tsvelik''
Tensor network simulations have emerged as a powerful algebraic framework for the simulation of strongly correlated quantum manybody systems. Their great appeal lies in the fact that they are exact in that they do no rely on small parameters. They significantly extend exact diagonalization to much larger system sizes in (effective) 1D or 2D all the way to the thermodynamic limit. I will give a brief introduction based on the hugely successful methods such as the numerical renormalization group (NRG) or the density matrix renormalization group (DMRG) with focus on multiorbital systems, both symmetric and nonsymmetric. A versatile numerical tool in that respect is my recently developed tensor library QSpace that can efficiently deal with generic symmetry settings including SU(N). After a brief motivation via the prototypical symmetric multiorbital system of iron impurities in gold or silver, I will present recent results on a dynamical meanfield theory (DMFT) study concerning the coherentincoherent crossover in ironpnictides, followed by recent work on the spin1 Heisenberg kagome lattice and preliminary results on SU(N) spin ladders.
CondensedMatter Physics & Materials Science Seminar
"From Molecular Beam Epitaxy to high magnetic field Quantum Oscillations"
Presented by Yoshiharu Krockenberger, NTT Basic Research Laboratories
Monday, March 21, 2016, 1:30 pm
Bldg.480 Conf. Rm
Hosted by: 'Ivan Bozovic'
Cuprate superconductors present a major challenge in condensed matter physics not only due to their electron correlations but also due to their complex crystal structure. Complex crystal structures, i.e. various cations at various lattice positions, demand for the utmost caretaking when synthesizing them. In particular, Molecular Beam Epitaxy is the foremost versatile tool and technique that allows for the synthesis of such materials without the necessity to compromise on impurity phases. First, I introduce our custom designed Molecular Beam Epitaxy equipment which is empowered by eguns, not effusion cells, and controlled by electron impact emission spectroscopy. After presenting several material systems I present high magnetic field quantum oscillation data on films synthesized by our Molecular Beam Epitaxy systems.
Nuclear Theory/RIKEN Seminar
"Duality, Dimensions and Reduction on the Lattice"
Presented by Joel Giedt, Rensselaer Polytechnic Institute
Friday, March 18, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Montonen and Olive found evidence that a duality could exist in YangMills with adjoint scalars. In this scheme, the 't HooftPolyakov monopole forms a gauge triplet with the photon, leading to a theory equivalent to the GeorgiGlashow model but with magnetic charge replacing electric charge. The duality is believed to be realized in N=4 superYangMills. We are pursuing numerical, nonperturbative evidence for this Sduality using our lattice formulation. Two lines of approach are being taken, which I will discuss. First, we attempt to show that there is a value of the gauge coupling for which the W boson mass is equal to the monopole mass. Second, we are relating the 't Hooft loop to the Wilson loop at this selfdual coupling. On a somewhat unrelated topic, we also discuss the determination of anomalous dimensions on the lattice. In the dual gravitational picture these correspond to masses of fields in the bulk, so that some aspects of the gaugegravity duality could be tested by such determinations. In particular in N=4 superYangMills there are predictions for the dimensions of nonprotected operators at the selfdual point, based on the superconformal bootstrap.
Physics Colloquium
"Hotdense Lattice QCD: Supercomputing Extreme Matter"
Presented by Swagato Mukherjee, BNL
Tuesday, March 15, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: 'Rob Pisarski'
I will discuss the role of supercomputing in revealing the phases and properties of the hotdense quarkgluon matter created during relativistic heavyion collisions. I will present a brief overview of the recent achievements of abinitio lattice Quantum Chromodynamiecs computations at nonzero temperatures and densities.
CondensedMatter Physics & Materials Science Seminar
"Realspace Visualization of the Superconducting Proximity effect and Josephson tunneling on Nanosized Pb thin film"
Presented by Howon Kim, Institute for Solid State Physics, University of Tokyo, Japan
Wednesday, March 9, 2016, 11 am
ISB Bldg. 734 Conf. Rm. 201 (upstairs)
Hosted by: Kazuhiro Fujita
The proximity and Josephson effects are wellknown phenomenon and widely used terms in superconductivity. Due to the recent advances in fabrication techniques those phenomenon has been extensively studied to give a new insight to the superconductorbased device applications. Nevertheless, many of these works addressed macroscopic properties of the samples, and thus local information is still missing. In this talk, I will discuss how we can realize the proximity effect and Josephson effect using scanning tunneling microscope at a nanometer scale. In the first part of the talk, we address how the local surface structure can influence on the proximity effect at the interface between superconducting twodimensional Pb islands and a singleatomiclayer metal by performing local tunneling spectroscopy. From the spectroscopic mapping taken around the Pbbased S/N interface, we observed the gap at the Fermi energy, reminiscent of the superconducting gap, propagating into the metal region (proximity effect) and its depth decaying with the distance from the interface. Additionally, we observed that the propagation of the gap is terminated by the steps of the substrate and enhancement of the gapdepth in the area between the interface and the step edge. The experimental results are compared with the results of quasiclassical theory based on the Usadel equation. [1] The second part of the talk addresses atomicscale SS junctions by using scanning tunneling microscopy and spectroscopy. In our local conductance measurements between superconducting Pb islands on Si(111) or Ge(111) and Pb layers on the end of PtIr tip apex, we observed evolution of not only the normalstate conductance [2] but also a zerobias peak (ZBP) from tunnel to atomic contact, which corresponds to the Josephson current, with a decrease in the tipsubstrate distance on the different atomic sites on the surface crystalline lattice of the substrate. With a help of multiple Andreev reflectio
Environmental & Climate Sciences Department Seminar
"Plant respiration: lessons from high latitudes for ecosystem carbon balance modelling"
Presented by Paul P. Gauthier, Princeton University
Wednesday, March 9, 2016, 11 am
John Dunn Seminar Room, Bldg. 463
Hosted by: Alistair Rogers
Climatemediated changes in ecosystem C balance are accepted as an important component of the biosphere response to climate change. Plant respiration and photosynthesis are major drivers of this balance but our lack of understanding of the controls and constrains surrounding their interaction stalls our capacity to predict future ecosystem changes. Using a new O2 isotopes method for measuring leaf functional traits, I will present a new approach to estimate the rate of leaf respiration in the light and its biochemical origin in temperate and arctic plants. The role of plant respiration as a key player for plant adaptation will also be discussed in the context of plant respiration modelling.
RIKEN Lunch Seminar
"Investigation of anomalous dynamics and the Chiral Magnetic Effect far from equilibrium"
Presented by Niklas Mueller, University of Heidelberg
Thursday, March 3, 2016, 12:30 pm
Building 510, Room 2160
Hosted by: Daniel Pitonyak
We investigate the impact of the AdlerBellJackiw axial anomaly on the realtime dynamics of gauge theories in the strong field regime. By studying and comparing Abelian gauge theories, such as QED, with nonAbelian systems, we try to clarify the role of topological properties and initial conditions relevant far from equilibrium. We show that the Abelian version of the Chiral Magnetic Effect, which has been predicted in the context of ultrarelativistic heavy ion collisions, can result in nontrivial experimental signatures, which could possibly be observed in future highintensity laser experiments. Further I will report on recent investigations of chiral production mechanisms in strong nonAbelian gauge fields and I will discuss the influence of topological objects such as sphalerons, far from equilibrium. Moreover I will show first results of the studies we have undertaken since my arrival here at BNL and discuss how the combination of these studies might be used to shed more light on the role played by anomalies in the early stages of a heavy ion collision.
Physics Colloquium
"Detection of Gravitational Waves and the First Observation of a Binary Black Hole Merger"
Presented by Imre Bartos, Columbia University
Tuesday, March 1, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Peter Petreczky
On September 14th 2015 the gravitational wave signature of a binary black hole merger was detected by the LIGO observatories. This marks the beginning of a completely new era of modern physics, the dawn of gravitationalwave astrophysics. We will discuss the discovery, its impact and its consequences.
Nuclear Physics Seminar
"Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC"
Presented by Paul Sorensen, BNL
Tuesday, March 1, 2016, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
I will present results from a harmonic decomposition of twoparticle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from 7.7 GeV to 200 GeV. v3 is studied as a function of the pseudorapidity di erence between particle pairs. Nonzero v3 is directly related to the previously observed large narrow ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity Quark Gluon Plasma (QGP) phase. For sufficiently central collisions, v3 persist down to an energy of 7.7 GeV suggesting that QGP may be created even in these low energy collisions. In peripheral collisions at these low energies however, v3 is consistent with zero. When scaled by pseudorapidity density of charged particle multiplicity per participating nucleon pair, v3^2 for central collisions shows a minimum near 20 GeV.
Particle Physics Seminar
"Observation of Gravitational Waves from a Binary Black Hole Merger by LIGO"
Presented by Sergey Klimenko, University of Florida
Monday, February 29, 2016, 3 pm
Large Seminar Room, Bldg. 510
Hosted by: Erin Sheldon
On September 14, 2015 at 09:50:45 UTC the Laser Interferometer Gravitationalwave Observatory (LIGO) Hanford, WA, and Livingston, LA, observatories detected a strong coincident signal. The signal matches the waveform predicted by general relativity for the inspiral merger of a pair of black holes and the ringdown of the resulting single black hole. A century after the fundamental predictions of Einstein and Schwarzschild, the gravitational waves are captured. I will present the details of this observation and discuss the results.
Nuclear Theory/RIKEN Seminar
"Real time method of thermal field theory"
Presented by Samir Mallik, Saha Institute of Nuclear Physics
Friday, February 26, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
I review the basic ideas of real time formulation of thermal field theory. Then I like to consider the following topics in this formulation: 1) thermal propagator for a scalar field 2) spectral representation of twopoint functions for arbitrary fields 3) perturbation expansion 4) oneloop self energy 5) dilepton production
Particle Physics Seminar
"Project 8: tritium decays, neutrino masses, and singleelectron spectroscopy"
Presented by Prof. Ben Monreal, UC Santa Barbara
Friday, February 26, 2016, 10 am
Small Seminar Room, Bldg. 510
Hosted by: Xin Qian
Beta decay kinematics are, in principle, sensitive to the absolute values of the neutrino masses. Many decades of work with tritium decay have shown m_nu to be in the range 0—2.0 eV; require improvement in spectrometer resolution, statistics, and systematics. The KATRIN experiment will push the limits of classical techniques to reach 0.2 eV sensitivity. The Project 8 is developing what we hope is the next step in beta electron spectroscopy; we can now perform precise electron energy measurements, insitu in a lowpressure gaseous source, by cyclotron radiation energy spectroscopy (CRES). I will show recent results from the Project 8 prototype, including the first CRES measurements in krypton, and our path to first molecular tritum measurements and to a future large atomic tritium experiment.
Particle Physics Seminar
"Giant detectors in solutionmined salt caverns"
Presented by Prof. Ben Monreal, UC Santa Barbara
Thursday, February 25, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Xin Qian
Many of particle physics' most interesting observables (neutrinos, dark matter, proton decay) require detectors installed underground. In many cases, the constraints associated with mines—limited roof spans, limited sites, safety, and excavation costs— are beginning to limit the scope of our experiments. The energy and chemical industries have 100 years of experience with a different type of underground space: solutionmined salt caverns. These are obtained by drilling into large salt formations and dissolving the salt with water. The caverns obtained can be enormous, deep, stable and above all inexpensive—but of course they have their own access and pressure constraints. In this talk, I will argue that a wide range of desirable detector technologies, including giant gas TPCs, might be deployed with these caverns. In particular, I will talk about an (untested) TPC gas mixture I devised with these caverns in mind, but which may prove useful in conventional labs too.
RIKEN Lunch Seminar
"Lambda_c  N interaction from lattice QCD"
Presented by Takaya Miyamoto, Yukawa Institute for Theoretical Physics, Kyoto University
Thursday, February 25, 2016, 12:30 pm
Building 510 Room 2160
Hosted by: Hiroshi Oki
Recently, a new approach to investigate hadron interactions in lattice QCD has been proposed[1] and developed extensively by the HAL QCD Collaboration[2]. This method can be easily applied to heavy baryon systems even though it is difficult to obtain experimental data of heavy baryons. We have investigated the interaction between Lambda_c and nucleon (N) from lattice QCD using the HAL QCD method. This is the first step to understand charmedbaryon interaction in lattice QCD. In this talk, we present the current status of our research project onLambda_cN interactions as well as future prospects. This talk is based on PoS (LATTICE 2015) 090.
Nuclear Theory/RIKEN Seminar
"Lattice QCD investigations of quark transverse momentum in hadrons"
Presented by Michael Engelhardt, New Mexico State University
Friday, February 19, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
An ongoing program of evaluating transverse momentum dependent parton distributions (TMDs) within lattice QCD is reviewed, summarizing recent progress with respect to several challenges faced by such calculations. These lattice calculations are based on a definition of TMDs through hadronic matrix elements of quark bilocal operators containing stapleshaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for a lattice calculation. Results presented include data on the naively Todd Sivers and BoerMulders effects, as well as the transversity and a wormgear distribution. Correlating quark transverse momentum with impact parameter, one can extract quark orbital angular momentum directly,including both the Ji as well as the JaffeManohar definitions.
Nuclear/Riken Theory Seminar
"The Transverse Structure of the Nucleon"
Presented by Marc Schlegel, University of Tuebingen
Friday, February 19, 2016, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Perturbative QCD based on the Parton Model of the nucleon is a very successful theoretical approach to describe highenergy processes at particle accelerators and colliders. In particular, parton distribution functions are key ingredients of this approach and give information on the partonic substructure of the nucleon. As such they deliver a onedimensional picture of how the parton momenta are distributed in the nucleon. In this talk extensions of the parton model are presented which provide access to more detailed information on the dynamics of partons in the nucleon. In particular observables involving transversely polarized nucleons are discussed. They can be described in terms of dynamical quarkgluon correlations which in turn can be studied at an ElectronIon Collider. Another extension of the parton model takes into account the intrinsic transverse motion of the partons. In this approach  called Transverse Momentum Dependent (TMD) factorization  one can study threedimensional distributions of the parton momenta. In addition, implications of the transverse motion of gluons in the nucleon will be discussed for LHC physics.
Particle Physics Seminar
"Weighing the Giants: Anchoring Cluster Cosmology"
Presented by Adam Mantz, SLAC National Accelerator Laboratory
Thursday, February 18, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Erin Sheldon
The gas mass fractions and the distribution in mass and redshift of the galaxy cluster population provide powerful probes of cosmology, constraining the cosmic matter density, the amplitude of the matter power spectrum, properties of dark energy, and the mass of neutrinos, among other parameters. Historically, these tests have been limited by the absolute accuracy of cluster mass determinations. Here, mass measurements from weak lensing have an advantage over estimates based on observations of the intracluster medium (ICM), because the former are nearly unbiased and can be straightforwardly tested against simulations. I will describe recent cosmological constraints obtained from an analysis of Xray selected cluster samples, incorporating extensive gravitational lensing data from the Weighing the Giants project — the first cluster cosmology study to consistently integrate a lensing mass calibration, including a rigorous quantification of all systematic uncertainties. The results highlight the power and potential of galaxy clusters, which constrain both the expansion of the Universe and the growth of cosmic structure, and their complementarity with other probes such as type Ia supernovae, largescale galaxy surveys, and the cosmic microwave background.
Physics Colloquium
"Physics opportunities at future circular colliders"
Presented by LianTao Wang, University of Chicago
Tuesday, February 16, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
Following the discovery of the Higgs boson, there has been a lot discussion about the next step in high energy physics. Among different options, a couple of newly proposed next generation circular colliders, including FCC at CERN and CEPC/SPPC in China, have attracted a lot of attention. Through preliminary studies in the past couple of years, an exciting picture of their physics capabilities has emerged. In this talk, I will give an overview on this topic, focusing on some of the most important questions in high energy physics they can help addressing
Nuclear Physics Seminar
"Precision Jet Physics to Probe Strong Dynamics"
Presented by Dr. Daekyoung Kang, Los Alamos National Laboratory
Tuesday, February 16, 2016, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
Jets produced in the high energy collision of quarks and gluons at colliders are bunches of collimated particles traveling along the same direction. Jet productions are extensively studied in various colliders in search for new physics beyond the standard model and as a probe of new state of matter like QGP. In this talk, I will discuss jet study at a high precision as a new tool to probe strong dynamics in electronproton collider. As an example, I will show the new tool can be used to determine the strong coupling constant and to improve our understanding of nuclear structure such as a parton distribution function of proton. With new level of precision not previously available for jets, the jet physics will provide one of milestones at the early stage of future ElectronIon collider.
Nuclear Theory/RIKEN Seminar
"Understanding the structure of hadrons through spin observables in hardscattering processes"
Presented by Daniel Pitonyak, BNL
Friday, February 12, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Almost all of the visible matter in the universe is built from hadrons, which are composed of quarks and gluons. One of the main challenges in nuclear physics is to understand this complex internal structure. In this talk, I will discuss how hardscattering processes that involve the spin of hadrons give us insight into aspects of their innerworkings that otherwise would be inaccessible. I will focus on phenomena that arise when hadrons carry spin transverse to their direction of motion, which allow us to examine them in 3D and analyze correlations between their quarks and gluons. I will also consider a new attempt to resolve the socalled "spin crisis" of how the proton gets its spin by looking at how much spin can be carried by smallx quarks and gluons.
CondensedMatter Physics & Materials Science Seminar
"BerezinskiiKosterlitzThoulesslike transition in a highly underdoped La2xSrxCuO4"
Presented by Dragana Popovic, NHMFL Tallahassee
Thursday, February 11, 2016, 1:30 pm
Bldg. 734, ISB Conf. Rm. 201 (upstairs)
Hosted by: Cedomir Petrovic
In twodimensional superconductors, the transition to the metallic state takes place via thermal unbinding of vortexantivortex pairs, as described by the BerezinskiiKosterlitzThouless (BKT) theory. The occurrence of the BKT transition in bulk underdoped samples of cuprate superconductors, which are highly anisotropic, layered materials, has been controversial. Therefore, the nature of the superconducting transition in highly underdoped thick films of La2xSrxCuO4 has been investigated using the inplane transport measurements. Both the temperature dependence of the paraconductivity above the transition and the nonlinear currentvoltage (IV) characteristics across it exhibit the main signatures of the BKT transition. Moreover, the quantitative comparison of the superfluid stiffness, extracted from the IV data, with the renormalizationgroup results for the BKT theory, reveals a large value of the vortexcore energy, strongly suggesting that the relevant length scale controlling the BKTlike transition in this layered material involves a few coupled layers. Finally, measurements of the fluctuations of the resistance with time (i.e. noise) provide evidence for the critical slowing down of the dynamics and the onset of correlated behavior. The details of the observed dynamical critical behavior of the BKT transition and the role of disorder will be discussed.
Center for Functional Nanomaterials Seminar
"In situ studies of nucleation and growth of nanoparticles under realistic conditions"
Presented by Elena Schevchenko, Argonne National Laboratory
Monday, February 8, 2016, 11 am
Conference Room A, Bldg. 735
Hosted by: Oleg Gang
The progress in colloidal synthesis allowed reaching a high degree of controls in synthesis of nanoparticles. As a result, nanoparticles come in many different shapes, sizes and compositions. Combining multiple components within individual nanoparticles or doping of nanoparticles are simple ways to control chemical and physical properties at nanoscale to obtain efficient catalysts and advanced energy conversion and storage systems. However the successful synthetic protocols are based on empirical rules based on numerous trials and errors and often the mechanism of nucleation and growth of nanoparticles remains unclear. I will present in situ study on the nucleation and growth kinetics and the temporal changes in the crystal structure of the metal dumbbell NPs (e.g. CoPt3/Au, Pt/Au and PtFe/Au). Using synchrotron small and wideangle Xray scattering (SAXS/WAXS) techniques we were able to catch the transient stages of structural and volumetric changes of NPs. We found that in the early stage of the reaction intermediate core/shell heterostructure is formed prior to dumbbells. The transition of the core/shell into the dumbbell occurs via strain relaxation of the pseudomorphic Au shell resulting in the nucleation of a strainfree Au domain. I will discuss the formation and doping process of iron and iron oxide NPs in real time by in situ synchrotron Xray absorption spectroscopy. In our study we revealed that the mass flow of the metal triggered by oxidation is responsible for the internalization of the dopant (molybdenum) adsorbed at the surface of the host iron NPs. The new oxidation induced doping mechanism allows control over the doping levels by varying the amount of dopant precursor. Our in situ studies also showed that the dopant precursor substantially changes the reaction kinetics of formation of iron and iron oxide NPs.
RIKEN Lunch Seminar
"Kinetic regime of hydrodynamic fluctuations"
Presented by Yukinao Akamatsu, Stony Brook University
Thursday, February 4, 2016, 12:30 pm
Building 510 Room 2160
Hosted by: Hiroshi Ohki
Hydrodynamics is an effective theory of systems close to equilibrium. It has been applied to description of fireballs created in the heavyion collisions. With growing interests in fluctuation of observables, theoretical identification of its origin is crucial. One of such origins is thermal fluctuation required by the fluctuationdissipation theorem. In this talk, I will present a new insight into the thermal fluctuation of hydrodynamics by separating the hard and soft scales in a given background. As an illustration, we adopt the Bjorken expansion as a background. The kinetic description of hard modes allows us simple interpretation of renormalization, longtime tails, and fractional powers of derivative expansion.
Physics Colloquium
"The New Big Science: the Changing Research Ecology at US Materials Science Facilities"
Presented by Robert Crease, Stony Brook University and, Catherine Westfall, Michigan State University
Tuesday, February 2, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
"We talk about a phase shift that has taken place over the past few decades at US national labs, in which largescale materials science accelerators rather than highenergy physics accelerators became marquee projects at most major basic research laboratories in the postCold War era, accompanied by important changes in the character and culture of the research ecosystem at these laboratories. We consider some features, periodization, funding, and challenges of this phase shift, known as the "New Big Science."
Nuclear Theory/RIKEN Seminar
"New aspects of QCD dynamics at high density: Jet evolution in the QGP and wave turbulence""
Presented by Yacine MehtarTani, INT Seattle
Friday, January 29, 2016, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
An essential feature of the parton shower that form a jet evolving in vacuum is color coherence that suppresses large angle soft gluon radiation and thus, ensuing the collimation of the jet. In the presence of dense QCD matter jet constituents suffer a rapid color randomization and thus an alteration of color coherence: as a result a mediuminduced gluon cascade, that can be described by a classical Makovian process, develop at large angles with respect to the jet axis [3]. A remarkable phenomenon emerges from such a cascade: the energy spectrum (of jet constituents) exhibits a scaling behavior, akin to wave turbulence, characterized by a constant flow of energy from the forward energetic patrons towards low momentum gluons down to the temperature of the plasma where energy is dissipated [4]. This picture is in agreement with a recent CMS analysis of missing energy in asymmetric dijet events where the energy balance is recovered at large angles and very soft particles [5]. In the second part of the talk I will discuss radiative corrections to jet observables that were shown to exhibit large double logarithmic enhancements. Owing to a large separation of time scales we have shown that these large corrections can be reabsorbed in a renormalization of the jetquenching parameter q^, preserving the probabilistic picture of the parton cascade [6]. This result leads us to question the standard viewpoints of the coupling of jets to the medium: the naive perturbative approach based on a leading order calculation and the AdS/CFT correspondence for strongly coupled plasmas. I will briefly invoke in the final part of my talk the various questions that remain to be addressed. Indeed, despite the recent progress much remains to be understood about jet fragmentation in a dense medium in order to construct a systematic and predictive approach to jetquenching from first principles.
Nuclear Physics Seminar
"A Nuclear Physicist's Journey In Business: Lessons From the Front Office"
Presented by Daniel Magestro, Ph.D., International Institute for Analytics
Monday, January 25, 2016, 11 am
Large Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
Companies in every industry are continually increasing their usage of large data sets and advanced statistical methods to understand customers and markets, improve operations, and forecast future business needs. The corresponding business demand for skilled analytical talent and "data scientists" has created a large talent gap for many companies that is predicted to surpass 100,000 nationally. Much of the talent gap arises from the hybrid skill set needed by data scientists that combines problem solving, technical, and communication skills. I will argue that the uniquely broad skill set of research scientists, and particularly experimental physicists in large collaborations, can bridge the growing talent gap for truly innovative companies.
Particle Physics Seminar
"Cross correlations with CMB secondaries: constraining cosmological parameters and cluster astrophysics"
Presented by Nick Battaglia, Princeton University
Thursday, January 21, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Anze Slosar
High resolution CMB experiments, such as ACT, SPT, and the Planck satellite are making precision measurements of the secondary anisotropies caused by the thermal Sunyaev Zel'dovich (tSZ) effect from galaxy clusters. However, our ability to obtain cosmological information from this tSZ signal is limited by our theoretical understanding of the baryons in clusters and groups. I will discuss how crosscorrelation methods are providing new windows into the messy "Gastrophysics" of the intracluster medium and the potential for these methods to constrain various cosmological parameters.
Physics Colloquium
"A bottomup approach to modeling the sensory cortex"
Presented by Luca Mazzucato, Stony Brook University
Tuesday, January 19, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
In response to sensory stimulation, neurons can generate sequences of complex activation patterns. Yet, neurons in the sensory cortex are active even in the absence of overt sensory stimulation, producing a large amount of 'ongoing,' i.e. spontaneously generated, neural activity that is often indistinguishable from noise. Research in the last two decades suggests that ongoing neural activity may shed light on the architecture and dynamics of neural circuits. Here, I present a new framework encompassing both ongoing and stimulusevoked neural activity, combining hidden Markov model analysis of neural recordings with biologically realistic models of cortical networks based on spiking neurons. This framework has been applied successfully to the sensory cortex and can be extended to other cortical systems. In the taste system, it has revealed new properties of single neurons and of neural populations, including a reduction of multistability and neural dimensionality in response to sensory stimuli, pointing to the existence of local neural clusters (yet to be experimentally confirmed). Using the analytical tools of effective mean field theory, one can explain these properties as emergent features of the network dynamics.
Particle Physics Seminar
"Search for Higgs Bosons produced in association with top quarks with the ATLAS detector"
Presented by Professor Vivek Jain, SUNY Albany
Thursday, January 14, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Ketevi Assamagan
Due to the large measured mass of the top quark, the Yukawa coupling of the top quark (yt) is much stronger than that of other quarks. The observation of the tÂ¯tH production mode would allow for a direct measurement of this coupling, to which other Higgs production modes are only sensitive via loop effects. Since yt is expected to be close to unity, it is also argued to be the quantity that might give insight into the scale of new physics. Using various Higgs decay modes, we report on the status of this search using data collected with the ATLAS detector at 7 and 8 TeV collision energies.
RIKEN Lunch Seminar
"Confinement and Chiral symmetry breaking from an Interacting Instantondyon ensemble for 2 colors and Nf flavors"
Presented by Rasmus Larsen, Stony Brook University
Thursday, January 14, 2016, 12:30 pm
Building 510 Room 2160
Hosted by: Daniel Pitonyak
I will present numerical results based on an interacting ensemble of instantondyons, that explains the connection between chiral symmetry breaking and confinement. The instantondyons have the nice properties to behave as monopoles at low temperatures, and as instantons at high temperatures. We will see how the scaling behavior of the instantondyons creates a Polyakov loop dependent potential, which forces the Polyakov loop to the confining value as the density of dyons increases at lower temperatures. For 2 flavors we find that the dominating configuration in the ensemble exhibit a chiral symmetry transition at the same temperature as the confinement transition, within accuracy. The important factor in explaining confinement and chiral symmetry breaking is the density of the Instantondyons.
Physics Colloquium
"From neV to MeV: ShortRange Fermion"
Presented by Or Hen, Laboratory for Nuclear Science, MIT
Tuesday, January 12, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions, usually neutrons, to higher average momentum. In this talk I will present results from highenergy proton and electron scattering experiments, which show that shortrange interactions between the fermions form correlated, highmomentum, neutronproton pairs. Thus, in neutronrich nuclei the probability of finding a highmomentum (k>kFermi) proton (a minority Fermion) is greater than that of a neutron (a majority Fermion). This has wide ranging implications for atomic, nuclear, atomic, and astro physics, including neutrinonucleus interactions, the EMC effect, the NuTeV anomaly, the nuclear symmetry energy and more. This feature is universal for imbalanced interacting Fermi systems and can also be observed experimentally in twospin states ultracold atomic gas systems.
Nuclear Physics Seminar
"ShortRange Correlations in Nuclei â€" Current Status and Future Perspectives"
Presented by Or Hen, Laboratory for Nuclear Science, MIT
Tuesday, January 12, 2016, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
Results from recent experiments show that shortrange interactions between the fermions form correlated, highmomentum, neutronproton pairs. These pairs account for 20%  25% of the nucleons in medium and heavy nuclei and dominate the momentum distribution of nucleons above the Fermi momentum of the nucleus. The observed dominance of these ShortRange Correlated (SRC) pairs by neutronproton pairs shows the dominance of the tensor part of the nucleonnucleon interaction at short distances. Recent works have shown that the existence and nature of SRC pairs has wide ranging implications for atomic, nuclear and astro physics, including neutrinonucleus scattering, the EMC effect, the NuTeV anomaly, the nuclear symmetry energy. In this talk I will present the use of hard exclusive reactions for the study of SRCs, and discuss several open questions for nextgeneration experiment to address. I will present an experimental program based on proton, electron, and neutrino beams that can run at Dubna, GSI, JLab, Fermilab and perhaps even at BNL. I will also discuss the possibility of studying SRC pairs and their partonic structure at an EIC, using the method of spectator tagging in Quasielastic and DeepInelastic kinematics.
Particle Physics Seminar
"Reactor Antineutrino Flux and Spectrum"
Presented by Mr. Chao Zhang, BNL
Thursday, January 7, 2016, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Xin Qian
Nuclear reactors are one of the most intense, pure, controllable, costeffective, and wellunderstood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavors are quantum mechanical mixtures. Accurate knowledge of reactor antineutrino production was crucial for those reactor experiments to achieve their goals. With the newest measurements from Daya Bay, I will revisit our current understanding of reactor antineutrino flux and spectrum, and its implications to future experiments.
CondensedMatter Physics & Materials Science Seminar
"Electron Transport through a Proximitized Nanowire"
Presented by Leonid Glazman, Yale University
Thursday, January 7, 2016, 1:30 pm
Bldg. 734, ISB Conf. Rm. 201 (upstairs)
Hosted by: Alexei Tsvelik
Motivated by recent experiments on InAs nanowires with epitaxial Al we investigate the twoterminal conductance of a short proximitized nanowire. We identify the leading electron transport processes at zero applied magnetic field as well as at finite fields, which suppress the induced superconducting gap and drive the system towards the topological transition. In the conventional superconducting phase, the conductance is controlled by the sequential Cooper pair tunneling if the induced gap exceeds the charging energy of the nanowire, and by the elastic singleelectron processes if the gap becomes smaller than the charging energy. The latter mechanism yields smaller values of the linear conductance and strongly asymmetric Coulomb blockade peaks, which may explain some experimental findings. Finally, we develop a quantitative theory for the conductance evolution across the transition into the topologicallynontrivial phase.
Physics Colloquium
"Search for hidden sector and invisible particles in the decay of the Higgs boson"
Presented by Ketevi Assamagan, BNL
Tuesday, January 5, 2016, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Peter Petreczky
The discovery of a Higgs boson at the LHC opens new research areas for instance the search for beyondtheStandardModel physics in the decays of the discovered Higgs boson. In events with large missing energy associated with jets, we search for the vector boson fusion production of the Higgs boson with forward jets, and the Higgs boson decays to invisible particles that result in large missing energy in the detector. An interpretation is done for the search for dark matter as a weakly interacting massive particle (WIMP) in the Higgs boson decays. We further carry out a statistical combination with other searches of Higgs boson decays to invisible particles to improve sensitivity. The current ATLAS exclusion limit combining all these searches is the best limit so far at the LHC on the invisible decay of the Higgs boson and the Higgs portal dark matter. In data events with four leptons in the final state, consistent with the decay of the Higgs boson to four leptons, we search for lightbeyondtheStandardModel gauge boson Zdark that decay to a pair of same flavor and opposite sign leptons (electrons or muons): H > Z(Zdark) Zdark > 4l. The light gauge boson Zdark is predicted in extensions to the Standard Model to explain the muon g2 anomaly and provide a candidate for dark matter.
RIKEN Lunch Seminar
"Baryon interactions from Lattice QCD by Luscher's finite volume method and HAL QCD method"
Presented by Takumi Iritani, Stony Brook University
Thursday, December 17, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Hiroshi Oki
Both Luscher's finite volume method and HAL QCD method are used to analyze the hadronhadron interaction in lattice QCD. However, some systematic discrepancies are reported between them.For example, Luscher's method shows the bound states of both deuteron and dineutron at the heavy pion mass,while these channels are scattering states from HAL QCD method. In this talk, to understand the deviations between them, we investigate the baryon interaction from both methods with the same lattice setups.From a systematic comparison of two methods, we clarify the problems in the previous studies. We also discuss the improvement of the analyses.
Physics Colloquium
"Experimental study of chiral and matterantimatter symmetries at RHIC"
Presented by Aihong Tang, BNL
Tuesday, December 15, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Peter Petreczky
Symmetries and the physics laws that they dictate are fundamental in describing the physical world. In this talk I discuss two fundamental symmetries that are well suited to be studied at RHIC, namely, the chiral symmetry and the matterantimatter symmetry. Under the hot and dense condition at RHIC, quarks and gluons are set free from protons and neutrons, making it feasible for the chiral symmetry to be restored. A restored chiral symmetry is a necessary requirement for the Chiral Magnetic Wave (CMW), a novel QCD phenomena, to propagate. The CMW has experimental consequences — it leads to the separation of elliptic flow between charged pions, which will be discussed in this talk. On the other hand, the abundantly produced antimatter at RHIC offers a unique opportunity to study the matterantimatter symmetry. In particular the nuclear force between two antinucleons has not been measured previously, although the corresponding force for nucleons or nuclei has been well studied for decades. In this talk I will discuss the measurement of the nuclear force between two antiprotons and compare to that between protons. As direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, this result provides an elemental ingredient for understanding the structure of more complex antinuclear and their properties.
Nuclear Physics Seminar
"New surprises from RHICSpin: forward neutron transverse single spin asymmetry from p+A collisions from PHENIX"
Presented by Alexander Bazilevsky, BNL
Tuesday, December 15, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
A surprisingly large transverse single spin asymmetry (A_N) in forward neutron production was discovered during the first polarized proton RHIC run in 2002. It was immediately utilized for monitoring proton beam polarization in experimental collision regions at RHIC. Later it was shown that one pion exchange model for forward neutron production was successful to describe both cross section and A_N. RHIC new data from polarized proton on nucleus collisions from RHIC 2015 run brought new surprise  a strong dependence of the asymmetry on nucleus size (or charge). Results also were found to strongly depend on particle production in other rapidity regions, indicating that there might be multiple neutron production mechanisms generating single spin asymmetry.
CondensedMatter Physics & Materials Science Seminar
"Soft mode branches, quantum central peak, and strong isotropic negative thermal expansion above a perovskite quantum phase transition"
Presented by Jason Hancock, University of Connecticut
Monday, December 14, 2015, 1:30 pm
ISB Conf. Room 201 (upstairs), Bldg. 734
Hosted by: Mark Dean
The importance of perovskitestructured materials to modern science cannot be understated, as they harbor diverse behavior and landscape of novel competing and intertwined phases. The structural phases of perovskites are critical to defining the framework of electronic conduction and magnetic exchange pathways in this interesting and technologically relevant class of materials. Large, isotropic negative thermal expansion is known to exist in only a handful of materials, beginning with the discovery of ZrW2O8 in the 1990s. In 2010, perovskite fluoride ScF3 was discovered to have a similarly profound negative thermal expansion (NTE) effect, shrinking in response to heat over a 1000 K temperature window with a linear thermal expansion coefficient lower than 105/K. Another curious property of this material is the structural stability â€" ScF3 retains a simple cubic structure and four atom unit cell from cryogenic temperature to its high melting point of 1800 K. ScF3 material does not feature the interesting phase competition of electrons and spin enjoyed by many of its oxide and fluoride cousins and can be classified as an ionic insulator. However the superlative nature of the NTE effect has motivated us to dive deeply into the lattice dynamics using high energy resolution inelastic Xray scattering on strainfree single crystals. Surprisingly, we find that an entire optical mode branch circumscribing the Brillouin zone boundary softens to nearly zero frequency as the temperature T approaches T=0. ScF3 at T=0 thus sits in extreme proximity to a quantum phase transition. We interpret this result in the context of better studied trifluorides and examine in detail the disorder phase diagram. In addition, concomitant with softening of the optic branch, a quasielastic "central peak" (CP) emerges and strengthens toward low temperature, further bolstering the identification of a T=0 phase transition. The CP phe
Nuclear Theory/RIKEN seminar
"Evolution of gluon TMDs: from small to moderate x"
Presented by Andrey Tarasov, Jefferson Lab
Friday, December 11, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Recently we obtained an evolution equation for gluon TMDs, which addresses a problem of unification of different kinematic limits. It describes evolution in the whole range of Bjorken x and transverse momentum kâŠ¥. I plan to discuss this evolution equation and show how in different kinematic regimes it yields several wellknown and some previously unknown results.
Particle Physics Seminar
"Kinematic weak lensing"
Presented by Eric Huff, Ohio State University
Thursday, December 10, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Erin Sheldon
Kinematic measurements hold some promise of dramatically enhancing the prospects of traditional weak lensing. In this talk I outline the method and describe how it eliminates or suppresses the effects of traditional weak lensing systematic errors arising from shear calibration, photometric redshifts, and intrinsic alignments. I also discuss what it would take to scale kinematic lensing up to a level competitive with other advanced dark energy probes.
CondensedMatter Physics & Materials Science Seminar
"Magnetotransport in Weyl and Dirac Metals"
Presented by Gustavo Monteiro, Stony Brook University
Thursday, December 10, 2015, 1:30 pm
ISB Building, Room 201
Hosted by: Alexei Tsvelik
Dirac (Weyl) metals are characterized by the linear dispersion of electron quasiparticles, with the Dirac (Weyl) point hidden inside a Fermi surface. In this talk, I will refer to the socalled chiral kinetic theory to describe within the same framework both the negative magnetoresistance caused by the chiral magnetic effect (CME) and quantum oscillations in the magnetoresistance (SdH effect) due to the existence of the Fermi surface in these materials. I will also argue about the role of Fermi arcs and their contribution for the SdH modes. At last, I will discuss the relevance of obtained results to recent measurements on Cd As .
RIKEN Lunch Seminar
"Phase structure of lattice QCD with Wilson and twistedmass fermions including isospin breaking"
Presented by Derek Horkel, University of Washington
Thursday, December 10, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Hiroshi Oki
As the precision frontier of particle physics continues to develop, the field of lattice QCD has risen to the challenge. Modern lattice simulations, have increasingly included light nondegenerate up and down quark masses and electromagnetism. Previously answered questions about the vacuum structure of QCD on the lattice must be reexamined when these isospin breaking effects are included. If not careful, lattice practitioners may simulate in nonphysical phases which cannot be extrapolated to the continuum limit. Using chiral perturbation theory, I will discuss where these nonphysical phases can arise for Wilson and twisted mass fermions. I will also explain some of the complications which arise when tuning the up and down twisted quark masses to their critical values in the presence of electromagnetism.
Physics Colloquium
"What Stubs and Sparkles Will Tell Us About Exploding Stars"
Presented by Kate Scholberg, Duke University
Tuesday, December 8, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Peter Petreczky
When a massive star collapses at the end of its life, nearly all of the gravitational binding energy of the resulting remnant is released in the form of neutrinos. I will discuss the nature of the corecollapse neutrino burst and what we can learn about particle physics and about astrophysics from the detection of these neutrinos. I will cover supernova neutrino detection techniques in general, current supernova neutrino detectors, and prospects for specific future experiments.
Nuclear Physics Seminar
"Measurement of the transverse singlespin asymmetry in p+p>WÂ±/Z0 at RHIC"
Presented by Salvatore Fazio, BNL
Tuesday, December 8, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
We present the measurement of the transverse singlespin asymmetry of weak boson production in transversely polarized protonproton collisions at sâˆš=500 GeV by the STAR experiment at RHIC. The measured observable is sensitive to the Sivers function, one of the transverse momentum dependent parton distribution functions, which is predicted to have the opposite sign in protonproton collisions from that observed in deep inelastic leptonproton scattering. These data provide the first experimental investigation of the nonuniversality of the Sivers function, fundamental to our understanding of QCD. The measured observable is also sensitive to the currently unconstrained Sivers function for the seaquarks and to the evolution of the transversemomentum dependent distribution functions.
Nuclear Theory/RIKEN Seminar
"Semiclassics, complex saddles and real path integrals"
Presented by Tin Sulejmanpasic, North Carolina State University
Friday, December 4, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
I will discuss the use of semiclassics and instanton calculus and argue that, contrary to common wisdom, complex solutions of the equations of motion are a necessary ingredient of any semiclassical expansion. In particular, I will show that without the complex solutions semiclassical expansion of supersymmetric theories cannot be reconciled with supersymmetry. This has a natural interpretation in the PicardLefschetz theory.
RIKEN Lunch Seminar
"Sterile neutrino dark matter produced after the QCD phase transition"
Presented by Louis Lello, University of Pittsburgh
Thursday, December 3, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Daniel Pitonyak
Sterile neutrinos are SU(2) singlets that mix with active neutrinos via a mass matrix, its diagonalization leads to mass eigenstates that couple via standard model vertices. We study the production of sterile neutrinos in the early universe from pion decays shortly after the QCD phase transition in the absence of a lepton asymmetry. We introduce the quantum kinetic equations that describe their production, freeze out and decay and discuss the various processes that lead to their production in a wide range of temperatures assessing their feasibility as dark matter candidates. We consider the production of heavy neutrinos in the mass range < 140MeV from pion decay shortly after the QCD crossover including finite temperature corrections to the pion form factors and mass. We consider the different decay channels that allow for the production of heavy neutrinos showing that their frozen distribution functions exhibit effects from "kinematic entanglement" and argue for their viability as mixed dark matter candidates. We discuss abundance, phase space density and stability constraints and argue that heavy neutrinos with lifetime >1/H0 freeze out of local thermal equilibrium.
Physics Colloquium
"Exotic Hadrons"
Presented by Eric Swanson, University of Pittsburgh
Tuesday, December 1, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Peter Petreczky
A series of novel and unusual hadrons have been discovered since 2003. This talk will present an overview of these states with the purpose of learning what they reveal about the nonperturbative structure of Quantum Chromodynamics.
Nuclear Theory/RIKEN Seminar
"Transversity Distribution and Collins Fragmentation Functions with QCD Evolution"
Presented by Alexei Prokudin, Jefferson Lab
Friday, November 20, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
We study the transverse momentum dependent (TMD) evolution of the Collins azimuthal asymmetries in e+eâˆ' annihilations and semiinclusive hadron production in deep inelastic scattering (SIDIS) processes. All the relevant coefficients are calculated up to the nexttoleading logarithmic (NLL) order accuracy. By applying the TMD evolution at the approximate NLL order in the CollinsSoperSterman (CSS) formalism, we extract transversity distributions for u and d quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in backtoback dihadron productions in e+eâˆ' annihilations measured by BELLE and BABAR Collaborations and SIDIS data from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results, and illustrate the unpolarized quark distribution, transversity distribution, unpolarized quark fragmentation and Collins fragmentation functions depending on the transverse momentum and the hard momentum scale. We make detailed predictions for future experiments and discuss their impact.
HET/RIKEN Lunch Seminar
"Collider Phenomenology of the Right Handed Heavy Neutrinos"
Presented by Arindam Das, University of Alabama
Friday, November 20, 2015, 12 pm
Building 510 Room2160
Hosted by: Amarjit Soni
We study the collider signature of pseudoDirac heavy neutrinos in the inverse seesaw scenario, where the heavy neutrinos with mass at the electroweak scale can have sizable mixings with the Standard Model neutrinos, while providing the tiny light neutrino masses by the inverse seesaw mechanism. Based on a simple, concrete model realizing the inverse seesaw scenario, we fix the model parameters so as to reproduce the neutrino oscillation data and to satisfy other experimental constraints, assuming two typical flavor structures of the model and the different types of hierarchical light neutrino mass spectra. For completeness, we also consider a general parametrization for the model parameters by introducing an arbitrary orthogonal matrix and the nonzero Dirac and Majorana phases. We perform a parameter scan to identify an allowed parameter region which satisfies all experimental constraints. With the fixed parameters, we analyze the heavy neutrino signal at the LHC through trilepton final states with large missing energy and at the ILC through a single lepton plus dijet with large missing energy.
Brookhaven Women In Science (BWIS) Event
"Thousand Shades of Grey: From High School Intern to Medical Imaging Physics Graduate"
Megan Russ, University of Buffalo Toshiba Stroke and Vascular Research Center
Thursday, November 19, 2015, 4:30 pm
Large Seminar Room, Bldg. 510
Refreshments served before the talk.
RIKEN Lunch Seminar
"Viscous Velocity Gradient Correction to Thermal Photon Emission Rate at Strong Coupling"
Presented by Kiminad Mamo, University of Illinois at Chicago
Thursday, November 19, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Daniel Pitonyak
We compute the correction to the thermal photon emission rate in first order of shear components of fluid velocity gradients in nearequilibrium hydrodynamic plasma at strong coupling regime using the realtime SchwingerKeldysh formalism in AdS/CFT correspondence. We find that the gradient correction to the thermal photon emission rate at strong coupling is about 0.3  0.4 times of the equilibrium rate.
Physics Colloquium
"IceCube: the Highenergy Universe and Multimessenger Astrophysics with Neutrinos"
Presented by Imre Bartos, Columbia University
Tuesday, November 17, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Peter Petreczky
Astrophysical processes that produce the observed energetic cosmic particles (up to 10^20 eV) and highenergy gamma radiation involve extreme nonthermal acceleration, strongly constraining the list of possible sources. Nevertheless, the origin of the most energetic cosmic rays, and the electromagnetic emission mechanism in extreme sources such as gammaray bursts, are currently unknown. Neutrinos may well be the silver bullet to unravel these processes. They can reveal the hadronic nature of the emission, and due to their weak interaction they lead right back to the source. The IceCube neutrino observatory at the South Pole has recently discovered a cosmic flux of TeVPeV neutrinos, making the first step in lifting the curtain on cosmic particle accelerators. I will discuss recent multimessenger observational developments, and source candidates in the highenergy universe. I will describe plans and capabilities for the nextgeneration neutrino detector IceCubeGen2.
Nuclear Physics Seminar
"PHENIX measurements of single electrons from semileptonic charm and bottom hadron decays in Au+Au collisions"
Presented by Dr. Darren McGlinchey, University of Colorado, Boulder
Tuesday, November 17, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Jin Huang
Measurements of the modification of heavy quarks in heavy ion collisions provide constraints on energy loss in the Quark Gluon Plasma. The dead cone effect predicts a mass ordering to the modification, with the heavier bottom quark being less modified than the charm quark due to suppression of forward radiation. Therefore, measuring the modification of charm and bottom quarks separately can provide additional constraints on energy loss calculations. Previous PHENIX measurements of heavy flavor electrons indicated a substantial suppression relative to binary scaled p+p collisions at high transverse momentum. However, the inability to separate the contributions from charm and bottom hadron decays prevented a full understanding of the modification. Using the precise tracking capabilities provided by the PHENIX barrel Silicon Vertex Detector (VTX), we are now able to separate the contributions from charm and bottom hadrons to the measured heavy flavor electrons as a function of transverse momentum in Au+Au collisions at sqrt(s_NN)=200 GeV. These results will be discussed and compared with theoretical models.
Nuclear Theory/RIKEN Seminar
"Linearly resummed hydrodynamics from gravity"
Presented by Yanyan Bu, Ben Gurion University of the Negev
Friday, November 13, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Using fluid/gravity correspondence, we study allorder resummed hydrodynamics in a weakly curved spacetime. The underlying microscopic theory is a finite temperature \mathcal{N}=4 superYangMills theory at strong coupling. To linear order in the amplitude of hydrodynamic variables and metric perturbations, the fluid's stressenergy tensor is computed with derivatives of both the fluid velocity and background metric resummed to all orders. In addition to two viscosity functions, we find four curvature induced structures coupled to the fluid via new transport coefficient functions, which were referred to as gravitational susceptibilities of the fluid (GSF). We analytically compute these coefficients in the hydrodynamic limit, and then numerically up to large values of momenta. We extensively discuss the meaning of all order hydrodynamics by expressing it in terms of the memory function formalism, which is also suitable for practical simulations. We also consider GaussBonnet correction in the dual gravity, which is equivalent to some 1/N corrections in the dual CFT. To leading order in the GaussBonnet coupling, we find that the memory function is still vanishing.
Joint RIKEN Lunch/HET Seminar
"Gluonfusion Higgs production: the final frontier"
Presented by Elisabetta Furlan, ETH, Zurich
Thursday, November 12, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Tomomi Ishikawa
The gluonfusion Higgs production cross section has been recently computed through the nexttonexttonext to leading order (N^3LO) in QCD. This unprecedented level of accuracy is crucial to exploit fully the LHC data in the validation of the Standard Model and in the search for potential (small) deviations due to new physics. I will give an overview of the tools that we employed to achieve this result, from the framework of heavyquark effective theories to the analytical and mathematical machinery that we developed. I will conclude with some results and future prospects.
Nuclear Theory/RIKEN Seminar
"Massless QED in three dimensions with even number of flavors"
Presented by Rajamani Narayanan, Florida International University
Friday, November 6, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Massless QED in three (two space and one Euclidean time) with even number of flavors does not break parity. There are analytical arguments for chiral symmetry to be spontaneously broken and some numerical evidence supporting these arguments. An interesting "open" question is the possibility of a critical number of flavors below which chiral symmetry is broken. Numerical results obtained using dynamical Wilson fermions will be presented with emphasis on the behavior of the low lying eigenvalues of the Wilson Dirac operator. Finite volume analysis will be used to obtain conclusions about the absence or presence of a chiral condensate.
Particle Physics Seminar
"LAr TPC data reconstruction"
Presented by Dorota Stefan, CERN/NCBJ Warsaw Poland
Thursday, November 5, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Elizabeth Worcester
In recent years, there is much interest in building massive liquid argon time projection (LAr TPC) detectors to measure among others CP violation in leptonic sector, search for nucleon decay and study a corecollapse supernova via neutrinos. Data collected by ICARUS and ArgoNuet proved that LAr TPC calorimetric and spatial resolutions are excellent. The detector technology with no doubts is much advanced, resulting with plans for the next generation of liquid argon experiments: the short baseline (SBN) and the long baseline (DUNE) are on the horizon. The LAr TPC evolved from the bubble chambers preserving the high resolution of tracking. Data analysis requires automatic event reconstruction that can understand and efficiently use the high granularity images provided by detector. The talk will cover the most recent advances in the reconstruction techniques, and also possible ways of developments since we are still on the way towards the ultimate tool for the optimal data analysis.
CondensedMatter Physics & Materials Science Seminar
"Pixelated detection in Differential Phase Contrast Interesting properties of pixelated STEM"
Presented by Matus Krajnak, University of Glasgow, United Kingdom
Thursday, November 5, 2015, 11 am
Bldg.480 Conf. Rm
Hosted by: Yimei Zhu
The application of differential phase contrast (DPC) imaging to the study of polycrystalline magnetic thin films and nanostructures in scanning transmission electron microscopy (STEM) has been hampered by the strong diffraction contrast resulting from the granular structure of the materials. In my talk I will demonstrate how a pixelated detector has been used to detect the bright field disk in aberration corrected STEM. I will explain subsequent processing of the acquired data, which allows efficient enhancement of the magnetic contrast in the resulting images. Initial results from a charged coupled device (CCD) camera demonstrate the highly efficient nature of this improvement over previous methods. Further hardware development with the use of a direct radiation detector, the Medipix3, also shows the possibilities where the reduction in collection time is more than an order of magnitude compared to the CCD. This allows subpixel measurement of the beam deflection due to the magnetic induction. Whilst the detection and processing is data intensive we have demonstrated highly efficient DPC imaging whereby pixel by pixel interpretation of the induction variation is realised with great potential for nanomagnetic imaging. In my talk I will also show advantages of using pixelated DPC in imaging of magnetic skyrmion structures in single crystal FeGe helimagnet which can provide their inner structure. I will advocate for pixelated STEM and explain how advantageous it can be in standard experiments and point to some new developments which it can provide.
CAD Accelerator Physics Seminar
"On the Development, Characterization, and Application of New Extraction Chromatographic Resins"
Presented by Dr. Steffen Happel, TRISKEM
Monday, November 2, 2015, 4 pm
Bldg. 911B, Large Conf. Rm. Rm.A202
Hosted by: Dmitri Medvedev
Â«An overview will be given over a number of new extraction chromatographic resins that have been developed over the last few years. Further to characterisation data (mainly DW values of selected elements) their application in various domains will be discussed. Examples given will include decommissioning and radioactive waste monitoring (e.g. Cl36/I129 and Sn126), environmental monitoring (e.g. direct extraction and separation of Pb and Sr from aqueous samples) and the production of isotopes for medical purposes (e.g. production of Cu isotopes from Ni or Zn targets, the separation of Zr from Y targets and the separation of Sn from large Cd targets)."
Nuclear Theory/RIKEN Seminar
"Observable consequences of eventbyevent fluctuations of HBT radii"
Presented by Christopher J. Plumberg, Ohio State University
Friday, October 30, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
One of the major lessons from the field of heavyion physics in the past several years has been the significance of the role played by eventbyevent fluctuations in the evolution of a heavyion collision. Their important effects on many momentumspace observables (particle yields and spectra, anisotropic flows, etc.) have already been studied systematically, and some of the properties of their eventbyevent distributions, and their consequences for the extraction of medium properties such as the specific viscosity of the quarkgluon plasma (QGP), are already known. In this talk it is pointed out that similar eventbyevent fluctuations of spatiotemporal observables provide complementary constraints on our understanding of the dynamical evolution of heavyion collisions. The relation of Hanbury BrownTwiss (HBT) radii extracted from ensembleaveraged correlation function measurements to the mean of their eventbyevent probability distribution is clarified, and a method to experimentally determine the mean and variance of this distribution is proposed and demonstrated using an ensemble of fluctuating events generated with the viscous hydrodynamic code VISH2+1. The sensitivity of the mean and variance of the HBT radii to the specific QGP shear viscosity Î·/s is studied using simulations with the same code. We report sensitivity of the mean pion HBT radii and their variances to the temperature dependence of Î·/s near the quarkhadron transition at a level similar (1020%) to that which was previously observed for elliptic and quadrangular flow of charged hadrons.
CondensedMatter Physics & Materials Science Seminar
"The Internal Structure of a Vortex in a TwoDimensional Superfluid with Long Healing Length"
Presented by Igor Aleiner, Columbia University
Thursday, October 29, 2015, 2 pm
Bldg. 734, ISB Conf. Rm. 201
Hosted by: Alexei Tsvelik
We analyze the motion of quantum vortices in a twodimensional bosonic superfluid within Popov's hydrodynamic description. In the long healing length limit (where a large number of particles are inside the vortex core) the superfluid dynamics is determined by saddle points of Popov's action, which, in particular, allows for weak solutions of the GrossPitaevskii equation. We solve the resulting equations of motion for a vortex moving with respect to the superfluid and find the reconstruction of the vortex core to be a nonanalytic function of the force applied on the vortex. This response produces an anomalously large dipole moment of the vortex and, as a result, the spectrum associated with the vortex motion exhibits narrow resonances lying {\em within} the phonon part of the spectrum, contrary to traditional view. (in collaboration with O. Agam and A. Klein)
CondensedMatter Physics & Materials Science Seminar
"MITs, magnetism, and dopants: Probing the nanoscale using advanced STEM"
Presented by Jack Y. Zhang, University of California Santa Barbara
Thursday, October 29, 2015, 11 am
Bldg.480 Conf. Rm
Hosted by: Yimei Zhu
Perovskite oxides remain a material class with properties that are still difficult to predict. Strong electron correlations, coupling between electron, lattice, spin and orbital degrees of freedoms, combined with the versatility of the structure itself, result in a wide range of properties and unique emergent phenomena that only occur at heterointerfaces. Understanding the origin of these properties is the first step to successfully control and tailor these materials for useful application. To that end, we utilize the scanning transmission electron microscope to characterize a number of titanate and nickelate compounds, in order to develop a link between the atomic structure and electrical/magnetic properties. Using realspace and diffraction techniques, we can probe the local atomic structures of thin film interfaces and quantum wells. We also continue the development of using quantitative STEM intensities for precise and accurate determination of 3D dopant atom configurations. Using variable detector angles, we demonstrate an improvement in 3D dopant locations on a test sample.
Nuclear Theory/RIKEN Seminar
"Thermal photons from a modern hydrodynamical model of heavy ion collisions"
Presented by JeanFrancois Paquet, Stonybrook University
Friday, October 23, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Early fluiddynamical calculations of direct photon spectra and momentum anisotropy were found to be systematically smaller than measurements from the RHIC and the LHC, an observation that became known as the "direct photon puzzle". I will show that the use of a modern hydrodynamical model of heavy ion collisions and of the latest photon emission rates greatly improves agreement with both ALICE and PHENIX data, supporting the idea that thermal photons are the dominant source of direct photon momentum anisotropy in heavy ion collisions. The eventbyevent hydrodynamical model used includes, for the first time, both shear and bulk viscosities, along with second order couplings between the two viscosities. Calculations using different photon emission rates will be shown, including one that takes into account the effect of confinement on photon emission. The effect of both shear and bulk viscosities on the photon rates will be shown to have a measurable effect on the photon momentum anisotropy.
Particle Physics Seminar
"Light Sterile Neutrinos: An Experimental Overview"
Presented by Jonathan Link, Center for Neutrino Physics, Virginia Tech
Thursday, October 22, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Elizabeth Worcester
Persistent, unproven hints of an eVscale sterile neutrino have been around since the late 1990's, when the LSND signal was shown to be incompatible with the emerging 3neutrino oscillation framework. More recent results from MiniBooNE and T2K as well as reanalyses of reactor neutrino and gallium source data continue to suggest the possibility of this new physics, but no experiment has been able to definitively demonstrate or for that matter rule out their existence. This talk will review the current state of the sterile neutrino and examine one possible experimental test using a new reactor neutrino detector technology designed to address the particular challenges of a shortbaseline reactor neutrino experiment.
RIKEN Lunch Seminar
"Walking and conformal dynamics in manyflavor QCD"
Presented by Hiroshi Ohki, RIKEN BNL Research Center
Thursday, October 22, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Tomomi Ishikawa
We present our lattice results of SU(3) gauge theory with many flavors, in particular with Nf=8, as a model of a walking or conformal gauge theory. We study the scaling properties of various hadron spectra including the (pseudo)scalar, vector, and baryon channels. From the Nf dependence of the theory, possible signals of walking or conformal dynamics will be discussed.
HET/RIKEN Seminar
"Phenomenology of semileptonic Bmeson decays with form factors from lattice QCD"
Presented by Ran Zhou, Fermilab
Wednesday, October 21, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Tomomi Ishikawa
The exclusive semileptonic $B$meson decays $B\to K(\pi)\ell^+\ell^$, $B \to K(\pi)\nu\bar\nu$, and $B\to\pi\tau\nu$ are used to extract the CKM elements and probe new physics beyond Standard Model. The errors of the form factors used to be an important source of the uncertainties in the theoretical predictions. Recent developments in latticeQCD provide more accurate form factors and enable us to have better theoretical predictions. In this talk, I will present the latest latticeQCD results of the form factors in the semileptonic $B$meson decays processes. In addition, I will compare the theoretical predictions and recent experimental results. The tension between the Standard Model and semileptonic $B$meson decay experimental data will be discussed.
CondensedMatter Physics & Materials Science Seminar
"Three dimensional topological semimetal Cd3As2: insights from magnetooptical spectroscopy"
Presented by Ana Akrap, University of Geneva, Switzerland
Wednesday, October 21, 2015, 1:30 pm
Bldg. 480 Conf. Room
Hosted by: Chris Homes
Cd3As2 is a threedimensional Dirac semimetal, with two Dirac cones around the Gamma point shifted away from each other along the (001) direction. It is known that the Dirac cones appear due to band inversion, although their exact scale is not clear at the moment. I will talk about zerofield optical conductivity, and highfield magnetoreflectivity of this material, and address some of the open questions regarding the band structure.
CondensedMatter Physics & Materials Science Seminar
"TBA"
Presented by Sasa Dordevic, University of Akron
Tuesday, October 20, 2015, 1:30 pm
Building 734, Room 201
Hosted by: Cedomir Petrovic
Infrared and magnetooptical studies of topological insulators Spectroscopic techniques are an important tool in studies of novel materials. I will review recent infrared and magnetooptical studies of 3D topological insulators Bi2Se3, Bi2Te3, Sb2Te3 and Bi1xSbx. A number of issues will be discussed, such as the cyclotron resonance and its field dependence, electronic inhomogeneities, and electronphonon coupling. We find that in Bi2Se3 charge carriers are indeed strongly coupled to an optical phonon, causing its asymmetric (Fano) lineshape. Moreover, we show that the asymmetry of the phonon can be switched from negative to positive, with the application of magnetic field. This is the socalled Fano q reversal, which to the best of our knowledge has not been observed before in topological insulators.
CondensedMatter Physics & Materials Science Seminar
"GW+DMFT: a diagrammatically controlled ab initio theory of strong correlation in real materials"
Presented by Sangkook Choi, Rutgers University
Tuesday, October 20, 2015, 11 am
Building 734, Room 201
Hosted by: Robert Konik
The first principles description of stronglycorrelated materials is currently regarded as one of the greatest challenges in condensed matter physics. In contrast to the weaklycorrelated materials, oneparticle picture based on the Fermi liquid theory fails because electrons in stronglycorrelated materials are neither fully localized on the atomic sites nor fully itinerant in the crystal. One of the most successful approaches to stronglycorrelated materials is the dynamical mean field theory (DMFT). Its successes revived the interest in the longsought goal of achieving a diagrammatically controlled ab initio theory by combining GW and DMFT Feynman graphs. In this talk, I'll introduce GW+DMFT approaches and present our new methodology grounded on the combination of the quasiparticle selfconsistent GW approximation (QSGW) and DMFT. I will also show how QSGW+DMFT approach improves the spectral properties of opend and f shell systems in comparison to other theories. I will conclude with the challenges ahead and its potential roles in materials design.
Particle Physics Seminar
"Recent Results from the BaBar Experiment"
Presented by David Norvil Brown, University of Louisville
Thursday, October 15, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Ketevi A. Assamagan
The BaBar Experiment was initially designed to study CPViolation in Bmeson decays. However, due to the generalpurpose and highquality design of the detector, it has been utilized for studies of many topics beyond the weak flavor realm. I will present a selection of recent results from BaBar, including topics from B physics and beyond. The results selected include a first observation of a mode which is an interesting piece in the puzzle about baryonic Bmeson decays; a measurement of timedependent asymmetries in a Bmeson decay; a measurement of Collins asymmetries in u, d, and s quark fragmentation; and a search for longlived particles predicted in many beyond the Standard Model theories.
CondensedMatter Physics & Materials Science Seminar
Presented by Sergey Zvyagin, High Magnetic Field Laboratory, Helmholtz Center Dresden, Germany
Thursday, October 15, 2015, 1:30 pm
Building 734, Room 201
Hosted by: Cedomir Petrovic
Spin dynamics in triangularlattice antiferromagnets Cs2CuBr4 and Cs2CuCl4: highfield ESR studies Sergei Zvyagin Dresden High Magnetic Field Laboratory (HLD) HelmholtzZentrum DresdenRossendorf, Dresden, Germany A spin1/2 Heisenberg antiferromagnet (AF) on a triangular lattice is the paradigmatic model in quantum magnetism and in the focus of recent experimental and theoretical studies. Here, we present results of highfield electron spin resonance (ESR) studies of spin1/2 Heisenberg AFs Cs2CuCl4 and Cs2CuBr4 with distorted triangularlattice structures in magnetic fields up to 50 T [1]. In the magnetically saturated phase, quantum fluctuations are fully suppressed, and the spin dynamics is defined by ordinary magnons. This allows us to accurately describe the magnetic excitation spectra in both materials and, using the harmonic spinwave theory, to determine their exchange parameters. The approach has a broader impact and can be potentially used for any quantum magnet with reduced (e.g., by the staggered DzyaloshinskiiMoriya interaction) translational symmetry, resulting, as predicted, in emergence of a new exchange mode above Hsat. We found that a substantial zerofield energy gap, Î"~9.5 K, observed in the lowtemperature excitation spectrum of Cs2CuBr4, is present below and well above TN, being a characteristics of lowdimensional spincorrelated state. The experimental data are compared with results of model spinwavetheory calculations for spin1/2 triangular lattice AF. This work was supported by the DFG. [1] S. A. Zvyagin, D. Kamenskyi, M. Ozerov, J. Wosnitza, M. Ikeda, T. Fujita, M. Hagiwara, A. I. Smirnov, T. A. Soldatov, A. Ya. Shapiro, J. Krzystek, R. Hu, H. Ryu, C. Petrovic, and M. E. Zhitomirsky, Phys. Rev. Lett. 112, 077206, 2014
RIKEN Lunch Seminar
"pQCD thermodynamics with massive quarks"
Presented by Thorben Graf, Institut fÃ¼r Theoretische Physik, Johann Wolfgang GoetheUniversitÃ¤t
Thursday, October 15, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Daniel Pitonyak
Results for several thermodynamic quantities within the nexttoleading order calculation of the thermodynamic potential in perturbative QCD at finite temperature and chemical potential including nonvanishing quark masses are presented. These results are compared to lattice data and to higherorder optimized perturbative calculations to investigate the trend brought about by mass corrections. Furthermore, the equation of state for nonvanishing isospin density was investigated within the introduced framework and the findings are also presented.
Physics Colloquium
"Random Matrices in Physics"
Presented by Hans A. Weidenmuller, MaxPlanckInstitut fur Kernphysik, Heidelberg, Germany
Tuesday, October 13, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
What can we say about a physical system when we know next to nothing about it? In classical physics, the principles of thermodynamics and a few systemspecific parameters suffice to make predictions. In quantum physics, random matrices have similar predictive power. That approachreferred to as randommatrix theoryhas found wide applications in recent years, in quantum physics and beyond. The use of random matrices in quantum chaos, in complex manybody systems, in disordered systems and in quantum chromodynamics will be presented. Furher applications in physics and mathematics will be briefly mentioned.
Special Nuclear Theory Seminar
"Inclusive Hadron Production as a Probe of Saturation Physics on the Energy Frontier"
Presented by David Zaslavsky, Central China Normal University
Friday, October 9, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
With a foundation of almost two decades of theoretical research, the saturation formalism is widely considered a strong candidate to describe the behavior of smallx gluons in highenergy collisions. However, the formalism has proven difficult to test. There is a pressing need for precise numerical results from the saturation formalism to use in comparisons with collider data. Fortunately, recent progress in the cross section for inclusive hadron production in pA collisions shows that it may be just the kind of precise result the community needs. The calculation of the NLO corrections, starting in 2012, achieved impressive reductions in the theoretical and numerical uncertainties, although the result becomes negative at high pâŠ¥. Still, precise predictions at moderate pâŠ¥ can be made and tested, and could be strong evidence toward showing the viability of the saturation model. In this talk, I introduce the recent modifications to the dipole splitting functions that complete the NLO corrections and help offset the negativity observed in earlier results. I'll also present the latest numerical results for the full LO+NLO cross section, including the first comparison with LHC pilot run data. For forward rapidity at both RHIC and the LHC, we have found excellent agreement with the data throughout the range in which the calculation is valid.
CondensedMatter Physics & Materials Science Seminar
"TBATopological NodalLine Fermions in Strong SpinOrbit Metal PbTaSe2"
Presented by TayRong Chang, National Tsing Hua University Taiwan, Taiwan
Thursday, October 8, 2015, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)
Hosted by: Wei Ku
In a typical threedimensional metal, the lowenergy excitations are found on a twodimensional closed Fermi surface in momentum space. Topological semimetals, by contrast, can support onedimensional Fermi lines or zerodimensional FermiWeyl points, at locations in momentum space, where the valence and conduction bands touch. While the degeneracy points in Weyl semimetals are robust against any perturbation that preserves translational symmetry, nodal lines require protection by additional crystalline symmetries such as mirror reflection. In this talk, I will demonstrate the prediction of topological nodalline states in the noncentrosymmetric compound singlecrystalline PbTaSe2 with strong spinorbit coupling based on the firstprinciples electronic structure calculations. Remarkably, the spinorbit nodal lines in PbTaSe2 are not only protected by the reflection symmetry but also characterized by an integer topological invariant. Our theoretical analysis illustrate the physical mechanism underlying the formation of the topological nodalline states and associated surface states. The calculated surface states for (001) surface with Pbtermination are in good agreement with angleresolved photoemission (ARPES) measurements [1]. [1] arXiv:1505.03069, G. Bian, T.R. Chang, R. Sankar, et al.
Particle Physics Seminar
"Top Quark Precision Physics and the Fate of the Universe"
Presented by Andreas Jung, Purdue University
Thursday, October 1, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Ketevi A. Assamagan
The talk will discuss recent measurements in the top quark sector, the heaviest known elementary particle known so far, performed at the Fermilab Tevatron Collider and at the LHC. I will highlight Tevatron results that are competitive to those at the LHC, especially regarding the top quark mass and production asymmetry. The talk will also present CMS results on the top quark mass and Yukawa coupling. I will discuss the implications for the standard model electroweak sector regarding the vacuum stability. I will conclude with an outlook towards the high luminosity phase of the LHC and the CMS silicon detector upgrades required for the high luminosity phase.
Particle Physics Seminar
"Recent Results From Daya Bay"
Presented by Gaosong Li, Shanghai Jiao Tong University
Monday, September 28, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Elizabeth Worcester
The Daya Bay Reactor Neutrino Experiment is designed to measure the neutrino mixing angle ï±13 with unprecedented precision. The experiment utilizes multiple pairs of identical antineutrino detectors (ADs) at different baselines from three pairs of reactor cores to minimize systematic uncertainties. In 2012, Daya Bay made the first definitive measurement of a nonzero value for ï±13 using the first 55 days of data collected with six ADs by measuring the antineutrino rate deficit. With the final two ADs installed, Daya Bay resumed data taking in full 8AD configuration in late 2012. More than 1 (0.15) million electron antineutrino candidates had been collected with the near (far) site detectors by the end of 2013, significantly improving the precision on ï±13. In addition to precision measurement of neutrino oscillation parameters, analyses exploring various other physics potential are carried out. In this talk, I will present the latest results on neutrino oscillation parameters, the search for a light sterile neutrino and the measurement of reactor neutrino flux and spectrum.
CondensedMatter Physics & Materials Science Seminar
"Inelastic Neutron Scattering of Manganese Pnictide Compounds LaMnPO and CaMn2Sb2"
Presented by Daniel McNally, Stony Brook University/BNL
Monday, September 28, 2015, 11 am
Bldg. 480
Hosted by: Mark Dean
I will report on two different projects that used inelastic neutron scattering measurements to determine 1. The origin of the charge gap in LaMnPO [1] 2. The origin of the magnetic frustration in CaMn2Sb2 [2] 1. I present my inelastic neutron scattering measurements over a wide range of temperatures on a powder sample of the antiferromagnetic insulator LaMnPO, that exhibits long range antiferromagnetic order below TN = 375 K. I used these measurements to determine a) the strength of the intersite magnetic exchange interactions SJ1 = 34 meV, SJ2 = 10 meV b) the temperature Tmax = 700 K (>> TN) where 2D magnetic correlations are no longer important. I then present high temperature optical spectroscopy measurements on single crystals of LaMnPO that show a charge gap persists above TN and Tmax. These experimental results show that long range magnetic order and exchange interactions play only a limited role in the formation of the charge gap in LaMnPO. Instead, density functional theory plus dynamical mean field theory calculations show that Hund's coupling is critical for the formation of the charge gap in LaMnPO, as well as related square net Mn pnictide compounds such as BaMn2As2 [D.E. McNally et al. PRB 92 115142 (2015)]. I will show that this work supports the view that multiorbital electronic correlations are important in the isostructural iron pnictide based superconductors. 2. I present my inelastic neutron scattering measurements on single crystals of the antiferromagnetic insulator CaMn2Sb2, that forms a corrugated honeycomb lattice of Mn spins that order below TN = 85 K, rather low for a Mn pnictide compound. I observed sharp dispersive 3D spin wave excitations up to energy transfers of 25 meV. I used a Heisenberg model to analyze the excitations and determine the first, second and caxis exchange interactions J1, J2, Jc. I use the determined ratio J2/J1 = 0.17 to situate CaMn2Sb2 on the theoretical phase diagram of the ho
ATLAS/HET Joint Lunch Seminar
"Constraints on New Physics via Higgs Boson Couplings and Invisible Decays with the ATLAS Detector"
Presented by Ketevi Assamagan, Brookhaven National Laboratory
Friday, September 25, 2015, 12 pm
Building 510 Room 2160
Hosted by: Amarjit Soni
The ATLAS experiment at the LHC has measured the Higgs boson couplings and mass, and searched for invisible Higgs boson decays, using multiple production and decay channels with up to 4.7 fb$^{1}$ of $pp$ collision data at $\sqrt{s}=7$ TeV and 20.3 fb$^{1}$ at $\sqrt{s}=8$ TeV. In the current study, the measured production and decay rates of the observed Higgs boson in the $\gamma\gamma$, $ZZ$, $WW$, $Z\gamma$, $bb$, $\tau\tau$, and $\mu\mu$ decay channels, along with results from the associated production of a Higgs boson with a topquark pair, are used to probe the scaling of the couplings with mass. Limits are set on parameters in extensions of the Standard Model including a composite Higgs boson, an additional electroweak singlet, and twoHiggsdoublet models. Together with the measured mass of the scalar Higgs boson in the $\gamma\gamma$ and $ZZ$ decay modes, a lower limit is set on the pseudoscalar Higgs boson mass of $m_{A}>370$ GeV in the ``hMSSM'' simplified Minimal Supersymmetric Standard Model. Results from direct searches for heavy Higgs bosons are also interpreted in the hMSSM. Direct searches for invisible Higgs boson decays in the vectorboson fusion and associated production of a Higgs boson with $W/Z$ ($Z\to ll$, $W/Z \to jj$) modes are statistically combined to set an upper limit on the Higgs boson invisible branching ratio of 0.25. The use of the measured visible decay rates in a more general coupling fit improves the upper limit to 0.23, constraining a Higgs portal model of dark matter.
CondensedMatter Physics & Materials Science Seminar
"Singleatom Impurity Effects in Ironbased Superconductors"
Presented by Shuheng H. Pan, Institute of Physics, Chinese Academy of Sciences
Friday, September 25, 2015, 11 am
ISB Bldg. 734, Conf. Rm. 201 (upstairs)
Hosted by: Yimei Zhu
Impurities can break Cooperpairs into quasiparticles with energy states inside the superconducting gap. The characteristics of such ingap states reflect accordingly the properties of the superconducting ground state. Therefore, impurity effects in superconductors have always been important subjects in the fundamental study of superconductivity. A singleatom impurity is an ideal model for both experimental and theoretical study of impurity effects on superconductivity. With high resolution STM/S technique, such proposal has been successfully realized. In this talk, I will present some of our high resolution STM/S studies of singleatom impurity effects in ironbased superconductors and discuss their implications to the microscopic mechanism of ironbased superconductivity.
Particle Physics Seminar
"Time Delay Cosmology"
Presented by Eric Linder, Berkeley/LBNL
Thursday, September 24, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Anze Slosar
Thousands of strong gravitational lenses will be found by time domain surveys such as DES and LSST. Time delays between multiple images can be used to form a geometric time delay distance, a cosmological probe with some unique sensitivities and complementarities. I consider three aspects: 1) the cosmology impact, 2) the statistics challenge of accurate estimation of time delays between noisy, gappy lightcurves and recent results from LSST's blind Time Delay Challenge, and 3) optimization of limited followup resources. I will also present new theory and instrument concepts for cosmic redshift drift, a direct probe of cosmic acceleration with a Hubble time delay. Methods for both probes have interesting overlaps with exoplanet searches.
CondensedMatter Physics & Materials Science Seminar
"A Giant Phonon Anomaly associated with Superconducting Fluctuations in the Pseudogap Phase of Cuprates"
Presented by Yehua Liu, ETH, Switzerland
Thursday, September 24, 2015, 1:30 pm
Bldg 734, 2nd Fl Conference Room
Hosted by: Robert Konik
Recent observations of a Giant Phonon Anomaly at the onset of the pseudogap, has revealed another surprising property of this phase. The opening of the pseudogap in underdoped cuprates breaks up the Fermi surface, which in turn can cause a breakup of the superconducting dwave order parameter into two subband amplitudes and to a low energy Leggett mode due to phase fluctuations between them. This leads to a large increase in the temperature range of superconducting fluctuations due to an overdamped Leggett mode. Almost resonant scattering of intersubband phonons to a state with a pair of Leggett modes, causes anomalously strong phonon damping. In the ordered state, the Leggett mode develops a finite energy, suppressing the anomalous phonon damping but leading to an anomaly in the phonon dispersion.
Nuclear Theory/RIKEN Seminar
"Single inclusive particle production at NLO: revised and improved"
Presented by Alex Kovner, University of Connecticut
Friday, September 18, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
We discuss the recent improvement of the NLO calculation of single inclusive particle production in pA collisions within the CGC formalizm. The two points that have not been addressed previously, and are treated consistently in the current approach are the Ioffe time cutoff on the configurations that can participate in the scattering, and the careful treatment of the evolution interval.
Particle Physics Seminar
"CMB Constraints DM Annihilation/Sum of the neutrino masses from CMB observations"
Presented by Neelima Sehgal, Stony Brook University
Thursday, September 17, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Ketevi Assamagan
I will present the latest constraints on the properties of annihilating dark matter and on the sum of the neutrino masses from CMB observations. I will focus on what has been learned so far from the Planck satellite and current groundbased CMB experiments. I will also discuss what we can expect in the future in terms of constraining dark matter and neutrino properties from nearfuture groundbased experiments, such as Advanced ACTPol, and the planned DOE CMBS4 project.
CondensedMatter Physics & Materials Science Seminar
"Atomic spin chain realization of a model for quantum criticality"
Presented by Rianne van den Berg, Universiteit van Amsterdam, Netherlands
Thursday, September 17, 2015, 1:30 pm
Bldg 734, 2nd Fl Conference Room
Hosted by: Robert Konik
The ability to manipulate single atoms has opened up the door to constructing interesting and useful quantum structures from the ground up. On the one hand, nanoscale arrangements of magnetic atoms are at the heart of future quantum computing and spintronic devices; on the other hand, they can be used as fundamental building blocks for the realization of textbook manybody quantum models, illustrating key concepts such as quantum phase transitions, topological order or frustration. Stepbystep assembly promises an interesting handle on the emergence of quantum collective behavior as one goes from one, to few, to many constituents. To achieve this, one must however maintain the ability to tune and measure local properties as the system size increases. We use lowtemperature scanning tunneling microscopy to construct arrays of magnetic atoms on a surface, designed to behave like spin1/2 XXZ Heisenberg chains in a transverse field, for which a quantum phase transition from an antiferromagnetic to a paramagnetic phase is predicted in the thermodynamic limit. Siteresolved measurements on these finite size realizations reveal a number of sudden ground state changes when the field approaches the critical value, each corresponding to a new domain wall entering the chains. We observe that these state crossings become closer for longer chains, indicating the onset of critical behavior. Our results present opportunities for further studies on quantum behavior of many body systems, as a function of their size and structural complexity.
CAD Accelerator Physics Seminar
"Attainment of Electron Beam Suitable for Medium Energy Electron Cooling"
Presented by Dr. Sergei Seletskiy, BNLPhoton Science
Thursday, September 17, 2015, 11 am
Bldg 911B, Large Conf. Rm., Rm A202
""The Recycler Electron Cooler (REC) at Fermilab advanced the electron cooling to the MeVrange energies. The REC performance depended critically on the quality of electron beam. In my presentation I will describe various aspects of development of the REC and the techniques used to obtain the electron beam suitable for the cooling process."
Center for Functional Nanomaterials Seminar
"Fluctuation Electron Microscopy â€" probing higher order structural correlations in disordered materials by coherent diffraction Soft Matter Enhanced Electrochemical Energy Storage and 3D Photonic Crystals"
Presented by J. Murray Gibson, Department of Physics, Northeastern University, Boston
Thursday, September 10, 2015, 11 am
CFN, Building 735, 2nd floor  Seminar Conf. Rm.
Hosted by: Eric Stach
Center for Functional Nanomaterials J. Murray Gibson Department of Physics, Northeastern University, Boston Fluctuation Electron Microscopy â€" probing higher order structural correlations in disordered materials by coherent diffraction Soft Matter Enhanced Electrochemical Energy Storage and 3D Photonic Crystals Thursday, September 10, 2015 11:00 a.m. Seminar Room, 2nd Fl. The conventional paircorrelation function, measured directly from diffraction, is a powerful tool to measure shortrange order on the scale of chemical bonds and next neighbors. With sufficiently welldefined long range order, the 2body function clearly reveals symmetry and periodicity. Diffraction techniques have thus been incredibly successful at the shortrange in teaching us about the structure of liquids and amorphous solids, and at the other scale most of what we know about the crystalline structure of matter. However the 2body function has a potential "blind spot" for ordering at intermediate length scales, typically up to of order ten bond lengths. Studies of amorphous materials by other techniques suggest that there can be pronounced mediumrange ordering on the nanoscale and that it can significantly affect physical properties. It is now recognized that higherorder correlation functions (3 and 4 body) are far more sensitive to mediumrange order and that that they can be accessed experimentally from coherent diffraction experiments. One of the earliest techniques to examine this was fluctuation microscopy (FM), developed by Treacy and Gibson1 for electron microscopy (FEM) and applied early to demonstrate mediumrange order and the effect of annealing in amorphous germanium2. In more recent years, with the freer access to coherent sources of electrons and xrays, more people are using FEM and developing related techniq
CAD Accelerator Physics Seminar
"Multipass Energy Recovery Experiment at Jefferson Lab's CEBAF"
Presented by Dr. Todd Satogata, JLAB
Wednesday, September 9, 2015, 4 pm
Bldg. 911A, Snyder Seminar Room
"The CEBAF recirculating linac accelerator has recently completed 12 GeV upgrade development, and plans to commission full energy accelerator setup this fall. With upgrade commissioning nearly complete, there is a new collaboration between BNL and Jefferson Lab that is developing a proposal for a multipass energy recovery experiment. This talk summarizes the current state of 12 GeV CEBAF, technical challenges for multipass energy recovery, and collaboration goals and technical progress for this multipass energy recovery experiment."
Joint Nuclear Physics and Particle Physics Seminar
"Understanding the nature of neutrinos via neutrinoless doublebeta decay"
Presented by Wenqin Xu, Los Alamos National Laboratory
Tuesday, September 8, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Jin Huang
Neutrinos provide a critical portal to physics beyond the Standard Model, yet the nature of neutrinos is largely unknown, including the neutrino mass hierarcy and if neutrinos are Majorana particles. Majorana particles are fermions that are their own antiparticles. Neutrinos being Majorana particles would explicitly violate lepton number conservation, and would pave the way to understand the matterantimatter asymmetry in the universe. Neutrinoless doublebeta (0) decay is a hypothesized process where two neutrons decay into two protons and two electrons simultaneously without emitting neutrinos. It is possible only if neutrinos are Majorana particles, and it is the only feasible way to experimentally establish the Majorana or Dirac nature of neutrinos. The observation of 0 decay would also provide complementary information related to neutrino masses. After decades of experimental eorts, the next generation 0 decay experiments will have a signicant discovery potential to observe 0 decay, if neutrinos are indeed Majorana particles. In this talk, we will discuss the physics of neutrinoless double beta decay and review the experiments searching for it. We will focus on the Majorana Demonstrator, a 40kg modular Germanium detector array, which searches for 0 decay in 76Ge and aims at demonstrating a path forward to next generation 0 decay experiments.
Nuclear Theory/RIKEN Seminar
"Asymptotic freedom of gluons in the Fock space"
Presented by Stanislaw Glazek, University of Warsaw
Friday, September 4, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Asymptotic freedom of gluons is defined in terms of scaledependent renormalized QCD Hamiltonian operators that act in the Fock space. These operators are calculable in a new way [1,2], by solving a doublecommutator differential equation [3], where the derivative is with respect to a scale parameter defined within the renormalization group procedure for effective particles (RGPEP). The RGPEP equation and its solutions are invariant with respect to boosts and may serve as a tool in attempts to dynamically explain the parton and constituent models of hadrons in QCD. The thirdorder QCD solution of the RGPEP equation to be discussed [2], provides an explicit example of how asymptotic freedom of gluons is exhibited in the scaledependence of Hamiltonians as operators in the Fock space. This example also prepares ground for the fourthorder calculations of effective strong interactions using the same RGPEP equation [3], to facilitate Hamiltonian studies of many stronginteraction processes, e.g., those that involve heavy quarkonia in relativistic motion. Applications to other sectors of the Standard Model than the strong interactions await development, while only preliminary results are currently available in the domain of precise calculations in QED[4]. [1] Dynamics of effective gluons, S. D. Glazek, Phys. Rev. D63, 116006, 29p (2001). [2] Asymptotic freedom in the frontform Hamiltonian for gluons, M. GomezRocha, S. D. Glazek, arXiv:1505.06688 [hepph], to appear in Phys. Rev. D. [3] Perturbative formulae for relativistic interactions of effective particles, S. D. Glazek, Acta Phys. Pol. B43, 1843, 20p (2012). [4] Calculation of size for boundstate constituent
RIKEN Lunch Seminar
"Analytic solution of the Boltzmann equation in the early universe"
Presented by Jorge Noronha, University of Sao Paulo
Thursday, September 3, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Daniel Pitonyak
A general method for exactly computing the nonlinear collision term of the Boltzmann equation for a massless relativistic gas in a homogeneous and isotropic spacetime is presented. This approach is used to find an exact analytical solution of the nonlinear relativistic Boltzmann equation in a FriedmannRobertsonWalker spacetime. This solution can be used to investigate analytically the interplay between global expansion and local thermalization in rapidly evolving systems.
Nuclear Physics Seminar
"Orbital angular momentum and generalized transverse momentum distribution"
Presented by Mr. Yong Zhao, University of Maryland
Tuesday, August 25, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
Recent advances in theory have shown that it is possible to directly calculate the canonical quark and gluon orbital angular momentum contributions to the proton spin in lattice QCD. When boosted to the infinite momentum frame, the quark and gluon orbital angular momentum operators defined in the gaugeinvariant nucleon spin sum rule of X. S. Chen et al. are the same as those derived from generalized transverse momentum distributions. The latter reduce to the canonical orbital angular momenta in the lightcone gauge, and can be measured in highenergy scattering experiments. I will show that these orbital angular momentum operators can be defined locally, and discuss the strategies of calculating their matrix elements in lattice QCD.
Special Nuclear Theory/RIKEN seminar
"Thermodynamics and topology from lattice QCD"
Presented by Michael MullerPreussker, Humboldt University Berlin
Monday, August 24, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Recent efforts to investigate the thermodynamics of lattice QCD with N_f=2+1+1 fermion degrees of freedom at realistic strange and charm quark masses and at various up and down quark mass values within the framework of Wilson twisted mass fermion discretization are discussed. Comparing with recently published results in the N_f=2 case we are going to present results for the pseudocritical temperature and preliminary results on the way to the thermodynamic equation of state. Moreover, we would like to discuss various methods to determine the topological susceptibility as a function of the temperature.
Center for Functional Nanomaterials Seminar
"Caught in the Act! Live Observations of Catalysts Using Highpressure Scanning Probe Microscopy"
Presented by Irene M. N. Groot, Leiden Institute of Physics and Leiden Institute of Chemistry, the Netherlands
Friday, August 21, 2015, 10 am
CFN, Bldg. 735, first fl. conference room A
Hosted by: Anibal Boscoboinik
Center for Functional Nanomaterials Seminar Caught in the Act! Live Observations of Catalysts Using Highpressure Scanning Probe Microscopy Irene M. N. Groot Leiden Institute of Physics and Leiden Institute of Chemistry, the Netherlands Friday, August 21, 2015 10:00 am Bldg. 735 â€" Conf. Rm. A Recently it has become clear that essential differences can exist between the behavior of catalysts under industrial conditions (high pressure and temperature) and the (ultra) high vacuum conditions of traditional laboratory experiments. Differences in structure, composition, reaction mechanism, activity, and selectivity have been observed. These observations indicated the presence of the socalled pressure gap, and made it clear that meaningful results can only be obtained at high pressures and temperatures. However, most of the techniques traditionally used to study catalysts and their reactions were designed to operate under (ultra) high vacuum conditions. To bridge the pressure gap, the last years have seen a tremendous effort in designing new instruments and adapting existing ones to be able to investigate catalysts in situ under industrially relevant conditions. This talk focuses on the development of scanning probe microscopy for operando observations of active model catalysts. In our group, we have developed setups that combine an ultrahigh vacuum environment for model catalyst preparation and characterization with a highpressure flow reactor cell, integrated with either a scanning tunneling microscope or an atomic force microscope. With these setups we are able to perform atomicscale investigations of welldefined model catalysts under industrial conditions. Additionally, we combine the structural information from scanning probe microscopy with timeresolved mass spectrometry measurements on the gas mixture that leaves the re
Particle Physics Seminar
"New Optical Techniques for Studying Vacuum Birefringence"
Presented by Carol Y. Scarlett, Florida A&M University
Thursday, August 20, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Elizabeth Worcester
The search for Axions, a particle theorized to explain the lack of CP violation in strong physics and suspected to contribute if not explain galactic dark matter, has lead to eversensitive techniques to study induced vacuum birefringence. What remains an issue: many of the measurable parameters that could give evidence for this illusive particle scale with the square of the birefringent angle (proportional to the photonaxion coupling constant). This talk will look at new techniques that can generate measurables that scale linearly (first order) with an induced birefringence. This has the potential to extend significantly the range through which cavity experiments can probe the vacuum of space in performing searches for axions and other exotic particles.
Computational Science Center Seminar
"High Performance Spatial Queries and Analytics for Spatial Big Data"
Presented by Fusheng Wang, SUNY SB
Tuesday, August 18, 2015, 10:30 am
John Dunn Seminar Room, Bldg. 463
Support of high performance queries and analytics on large volumes of spatial data becomes increasingly important in many application domains, including geospatial problems and emerging scientific applications such as pathology imaging. There are two major challenges for managing and querying massive spatial data: the explosion of spatial data, and the high computational complexity of spatial queries due to its multidimensional nature. Our goal is to develop a general framework to support high performance spatial queries and analytics for spatial big data on MapReduce and CPUGPU hybrid platforms. In this talk, I will present a scalable and high performance spatial data warehousing system HadoopGIS for running large scale spatial queries on Hadoop and Spark. HadoopGIS achieves scalable and efficient queries through optimized spatial partitioning, multilevel indexing, customizable spatial query engine RESQUE and implicit parallel spatial query execution. I will introduce applications of the system to support pathology imaging analytics and social media analytics.
Nuclear Theory/RIKEN Seminar
"Initial state correlations, entanglement entropy and all that"
Presented by Michal Lublinsky, Ben Gurion University of the Negev
Friday, August 14, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
I will discuss high energy collisions of dilute on dense systems (pA) and review some ideas about initialstate induced correlations.
Particle Physics Seminar
"Exciting New Results From LHCb"
Presented by Sheldon Stone, Syracuse University
Thursday, August 13, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Elizabeth Worchester
LHCb has presented groundbreaking new results this summer in exotic particle spectroscopy and searches for new physics.
RIKEN Lunch Seminar
"Discrimination of large quantum ensembles"
Presented by Emilio Bagan, GIQ, Physics Dept., UAB, Spain and Hunter College of the CUNY
Thursday, August 13, 2015, 12:30 pm
Building 510, Room 2160
Hosted by: Daniel Pitonyak
"Hypothesis testing is arguably the most common and elementary task in information processing (e.g., we constantly make decisions based on incomplete information). Its quantum version, quantum state discrimination, is likewise central in quantum information processing. The talk gives an introduction to the topic, focussing on discrimination of a large amount of identically prepared systems. In this limit, a powerful bound on the error rate can be derived. In classical statistics this is know as Chernoff bound. The quantum version of the Chernoff bound will be presented and discussed."
Physics Colloquium
"Life after Physics: A look back on 20 years in Finance"
Presented by Andreas Gocksch
Tuesday, August 11, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Robert Pisarski
After 10 years of research in High Energy Theory this BNL graduate ('83'85 and '88'93) followed the call of Wall Street. In my talk I reflect on over 20 years in the financial industry with an emphasis on highlighting possible career choices for young people that might one day be faced with searching for a "life after Physics". Along the way I also hope to leave the audience with an understanding of some basic facts about Finance and an appreciation for the utility of the physicist's toolkit in the "real world". *This talk may be of especial interest to students.
HET/RIKEN seminar
"Higgs coupling deviations, vacuum stability and new bosons at the TeV scale"
Presented by Raffaele D'Agnolo, Institute for Advanced Study
Wednesday, August 5, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ChienYi Chen
Higgs coupling measurements can shed light on the nature of electroweak symmetry breaking. However it is not trivial to go beyond generic intuitions, such as the expectation that natural theories generate large deviations, and make precise statements. In this talk I will show in a model independent way that measuring deviations at the LHC implies the existence of new bosons between a few TeV and a few hundred TeV. This is true in general, including theories where new fermions produce the deviations.
Nuclear Theory/RIKEN seminar
"Generalized Landaulevel representation for spin1/2 fermions and its applications"
Presented by Igor Shovkovy, Arizona State University
Friday, July 31, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
I will discuss the recently proposed generalized Landaulevel representation for charged fermions in an external magnetic field. After demonstrating its key advantages over the other existing representations, I will mention several of its applications. One of them is the quantum Hall effect in graphene, where the new representation is essential for a sufficiently detailed theoretical description, in which all the dynamical parameters are running functions of the Landaulevel index. The other application is the chiral asymmetry induced in dense relativistic matter in an external magnetic field. The quantitative measure of such an asymmetry is the chiral shift parameter that measures a relative shift of the longitudinal momenta (along the direction of the magnetic field) in the dispersion relations of opposite chirality fermions. Using the language of solid state physics, the corresponding ground state of dense relativistic matter could be interpreted as a Weyl metal state. Incidentally, the exact same mechanism also works in real Dirac metals.
CAD Accelerator Physics Seminar
"Muon Accelerators: R&D Towards Future Neutrino Factory and Lepton Collider Capabilities"
Presented by Mark Palmer, Fermilab
Thursday, July 30, 2015, 3:30 pm
Building 911B, Large Conference Room, Second Floor
This talk will describe the evolution of Muon accelerator R&D. An overview of what has been accomplished under the U.S. Muon Accelerator Program (MAP), what remains to be done, and how the elements of the program are evolving will be presented.
RIKEN Lunch Seminar
"Podd Spectral Density at Weak Coupling: Photon Emission and Second"
Presented by HoUng Yee, University of Illinois at Chicago
Thursday, July 30, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Daniel Pitonyak
The Podd spectral density of current correlation functions appears in several physical observables which are related to chiral anomaly, and is a sensitive probe of microscopic dynamics which is less protected by symmetry alone. We discuss two examples of their appearance: photon emission and the second order transport coefficient from chiral anomaly. We describe leading order weak coupling computations for these examples.
Physics Colloquium
"Exotic and conventional hadrons from lattice QCD"
Presented by Sasa Prelovsek, University of Ljubljana, Jefferson Lab
Tuesday, July 28, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Rob Pisarski
Faced with the recent experimental discoveries of pentaquarks and tetraquarks, one would like to establish whether these states arise directly from the fundamental theory of strong interactions  QCD. I will present how the exotic and conventional hadrons are investigated with abinitio lattice QCD simulations. The approach will be illustrated with recent lattice results on the charmoniumlike states Zc and X(3872), conventional resonances, bound states and pentaquarks.
Nuclear Theory/RIKEN seminar
"Resumming large radiative corrections in the highenergy evolution of the Color Glass Condensate"
Presented by Edmond Iancu, CEA Saclay
Friday, July 24, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Speren Schlichting
The BKJIMWLK equations describing the evolution of the Color Glass Condensate with increasing energy have recently been extended to nexttoleading order (NLO) accuracy. However, some of the NLO corrections turn out to be extremely large, since amplified by (double and single) `collinear' logarithms, i.e. logarithms of ratios of transverse momenta. This difficulty points towards the existence of large radiative corrections to all orders in $\alpha_s$, as generated by the transverse phasespace, which must be computed and resummed in order to restore the convergence of the perturbative expansion. In a couple of recent papers, we developed a resummation scheme in that sense, which achieves a complete resummation of the doublelogarithmic corrections and a partial resummation of the singlelogarithmic ones (including the running coupling effects). We have thus deduced a collinearlyimproved version of the BK equation which includes the largest radiative corrections to all orders. To demonstrate the usefulness of this equation as a tool for phenomenology, for have used it for fits to the HERA data for electronproton deep inelastic scattering at high energy. We have obtained excellent fits with a reduced number of free parameters and with initial conditions at low energy taken from perturbative QCD.
High Energy Physics Seminar
"New results from the hydrogen channel in Double Chooz"
Presented by Rachel Carr, Columbia University
Thursday, July 23, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Elizabeth Worcester
Beginning in 2011, the Double Chooz experiment has produced increasingly precise measurements of the neutrino oscillation parameter sin22Î¸13. These measurements rely on the detection of reactor antineutrinos through the inverse beta decay (IBD) interaction. The most recent analysis uses IBD interactions followed by neutron capture on hydrogen, rather than the standard Gd capture channel. A new artificial neural networkbased signal selection, novel background rejection techniques, and reduced detection systematics make this analysis far more sensitive than the original Hchannel measurement in Double Chooz. The precision of this new sin22Î¸13 measurement approaches that of the Gdchannel measurement, demonstrating the possibility of performing highsensitivity physics measurements without a Gd dopant.
CondensedMatter Physics & Materials Science Seminar
"Discovery of Weyl fermions in condensed matter"
Presented by Hong Ding, Inst. of Physics, Chinese Academy of Sciences, China
Wednesday, July 22, 2015, 1:30 pm
Bldg. 734, ISB Conf. Room 201 (upstairs)
Hosted by: Peter D. Johnson
In 1929, a German mathematician and physicist Hermann Weyl proposed that a massless solution of the Dirac equation represents a pair of new type of particles, the socalled Weyl fermions. However, their existence in particle physics remains elusive after more than eight decades, e.g., neutrino has been regarded as a Weyl fermion in the Standard Model until it was found to have mass. Recently, significant advances in both topological insulators and topological semimetals have provided an alternative way to realize Weyl fermions in condensed matter as an emergent phenomenon. Weyl semimetals are predicted as a class of topological materials that can be regarded as threedimensional analogs of graphene breaking time reversal or inversion symmetry. Electrons in a Weyl semimetal behave exactly as Weyl fermions, which have many exotic properties, such as chiral anomaly, magnetic monopoles in the crystal momentum space, and open Fermi arcs on the surface. In this talk I will report our discovery of a Weyl semimetal in TaAs by observing Fermi arcs in the surface states and Weyl nodes in the bulk states using angleresolved photoemission spectroscopy.
CAD Accelerator Physics Seminar
""A Holistic Approach to Accelerator Reliability Modeling""
Presented by Miha Rescic, University of Huddersfield
Wednesday, July 22, 2015, 1:30 pm
Bldg 911B, Large Conf. Rm. Rm A202
Hosted by: Steve Peggs/Kevin Brown
"High reliability has become a crucial issue in the design and operation of accelerators due to the demands of specific applications (e.g. medical accelerators, neutron spallation sources, nuclear waste transmutation). This is particularly relevant for acceleratordriven neutron facilities and for AcceleratorDriven Systems technologies for waste transmutation. Until now, accelerator reliability analysis has mostly been performed using simplified methods either in the design phase of projects, or after the accelerator is operational. This talk discusses a holistic approach to accelerator reliability modeling using Hidden Markov Models to look for emergent behavior of the accelerator, using systemcomplexity agnostics datasets from the operating machine, e.g. beam current or charge."
CondensedMatter Physics & Materials Science Seminar
"Imaging and Understanding AtomicScale Surface Interactions: Quantitative Investigations Using In Situ Electron Microscopy"
Presented by Prof. Tevis Jacobs, University of Pittsburgh
Monday, July 20, 2015, 1:30 pm
Conference Room, Building 480
Hosted by: MyungGeun Han
The atomicscale mechanisms that govern the adhesion, mechanical deformation, and bonding of surfaces in contact are not well understood. Yet accurate description and prediction of such contact phenomena is critically important in advanced nanoscale applications, including scanning probe microscopy (e.g., nanoscale mapping of mechanical and functional properties), micro/nanoelectromechanical systems (e.g., actuators, switches), and nanomanufacturing processes (e.g., scanning probe lithography). In this talk, I will discuss contact and sliding tests on nanoscale tips of silicon and other technologically relevant materials. These tests were performed inside of a transmission electron microscope (TEM), enabling in situ interrogation of a contact interface while controlling the displacement of the bodies and measuring normal forces with subnanonewton resolution. Quantitative data were extracted using custom analysis routines to resolve the geometry of the contacting bodies, adhesive forces, and volumes removed due to sliding wear, all with unprecedented resolution. In the first part of the talk, TEM adhesion tests of carbonbased coatings on diamond performed using this setup will be discussed. Subnanonewton force resolution was paired with Angstromscale measurements of asperity geometry. Combined with complementary molecular dynamics simulations, these results revealed an orderofmagnitude reduction in apparent work of adhesion as tip roughness increased from atomicscale corrugation to a rootmeansquare value of 1 nm. These results demonstrate the strong effect of subnanoscale topography on adhesion, and highlight a key limitation of conventional approaches for measuring the work of adhesion. In the second part of the talk, in situ sliding tests of silicon tips sliding on diamond at low applied loads reveal that wear occurs by atomic attrition: gradual material removal at the atomic scale. The process can be accurately described using stress
Nuclear Theory/RIKEN seminar
"The LPM effect in energy loss and sequential bremsstrahlung"
Presented by Peter Arnold, University of Virginia
Friday, July 17, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Highenergy particles passing through matter lose energy by showering via hard bremsstrahlung and pair production. At very high energy, the quantum duration of each splitting process, known as the formation time, exceeds the mean free time for collisions with the medium, leading to a significant reduction in the splitting rate, known as the LandauPomeranchukMigdal (LPM) effect. A longstanding problem in field theory has been to understand how to implement this effect in cases where the formation times of two consecutive splittings overlap. I will review why this question is interesting and discuss recent progress in the context of jet energy loss in quarkgluon plasmas.
Instrumentation Division Seminar
"Design of specific high speed converters at LPSC Grenoble"
Presented by Daniel Dzahini, Laboratory of Subatomic Physics and Cosmology, Grenoble, France
Wednesday, July 15, 2015, 2:30 pm
Large Conference Room, Bldg. 535
This presentation will describe the design of specific high speed and high resolution converters in LPSC Grenoble. ADC designs for calorimeters and different pixels detectors will be discussed in detail. Trends and constraints for future converter designs in DSM process will also be described.
CondensedMatter Physics & Materials Science Seminar
"Revisiting Josephson junction phase dynamics and its codes"
Presented by Francesco Tafuri, Seconda UniversitÃ di Napoli & CNRSPIN, UnitÃ di Napoli, Italy
Monday, July 13, 2015, 1:30 pm
Bldg. 480 Conference Room
Hosted by: Ivan Bozovic
The Josephson effect is still a unique key towards a variety of frontier problems ranging from the detection of Majorana fermions to macroscopic quantum phenomena and qubit applications. Progress in material science in producing a larger variety of interfaces and in nanotechnologies applied to superconductivity, may promote a renewal on the paradigms of the phase dynamics of Josephson junctions with relevant consequences on a series of key issues. We will discuss some relevant experiments mostly realized on unconventional junctions, including hybrid devices, nanojunctions, and especially high critical temperature superconductors (HTS). Novel phenomena emerge because of the possibility of driving materials and junctions with an accurate control in unexplored regimes. We have investigated different microstructural configurations, which offer a wide range of junction dynamical parameters. A transition from classical Josephson phase dynamics, which takes place in junctions characterized by low values of critical current density Jc, to a regime in which dissipation is driven by local heating processes, for high values of Jc. We demonstrate how nonequilibrium effects and local processes in constrained geometry are codified in the response of the junctions and can be disentangled from other effects. Escape dynamics turns as an active 'imaging' of nanoscale transport with an enormous potential and the ability of encoding subtle transport information in fluctuations. We speculate on possible intrinsic nanoscale ordering occurring in HTS systems. This transition is of relevance for all kinds of weak links including the emergent family of nanohybrid junctions. Information on the search of quantum phase slips can be also derived. Experiments on reference systems as HTS nanowires and Josephson junctions with ferromagnetic spinvalve tunnel barriers (experiment made in collaboration with University of Cambridge) will be finally
CAD Accelerator Physics Seminar
""Cascaded Longitudinal Space Charge Amplifier for ShortWavelength Radiation Generation at Fermilab's ASTA""
Presented by Aliaksei Halavanau, Northern Illinois University
Friday, July 10, 2015, 11 am
Bldg 911B, Large Conf. Rm., Rm. A202
"Longitudinal space charge (LSC) effects are generally considered as detrimental in freeelectron lasers as they can seed unwanted energy modulations and emittance growth. There has however been an increasing interest in devising accelerator beam lines capable of sustaining this LSC instability as a mechanism to operate as a coherent light source. In such a cascaded longitudinal space charge amplifier (LSCA), initial noise present in the beam density is amplified via the interplay of longitudinal space charge forces and properly located dispersive sections. To date most of these studies have been carried out with a onedimensional impedance model for the LSC. We use an available gridless threedimensional Nbody ``BarnesHut'' algorithm to simulate the 3D space charge force in the beam combined with ELEGANT and explore the limitations of the 1D model often used. We investigate, via numerical simulations, the performances of a cascaded LSCA beam line at the Fermilab's Advanced Superconducting Test Accelerator (ASTA)."
Nuclear Physics Seminar
"In search of old and new anomalous chiral effects in heavy ion collisions"
Presented by Jinfeng Liao, Indiana University
Tuesday, June 30, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
The heavy ion collision provides a unique manybody environment where local domains of strongly interacting chiral medium may occur. Certain anomalous transport processes, forbidden in usual medium, become possible in such domains. These anomalous chiral effects have their microscopic origin at the fundamental quantum anomaly and manifest themselves macroscopically in hydrodynamic currents. In the first part of this talk we report our recent finding (arXiv:1504.03201) of a new gapless collective excitation, called the Chiral Vortical Wave (CVW) in a rotating quarkgluon plasma. The CVW wave equation will be derived, and we show that its solutions describe nontrivial CVWinduced charge transport. We further propose and estimate possible experimental signals. In the second part of this talk we report our stateoftheart simulations of the longsoughtafter Chiral Magnetic Effect (CME), performed in the anomalous hydrodynamic framework and taking into account identified background contributions (arXiV:1504.06906). We discuss the implications of our results for the experimental search of CME
CondensedMatter Physics & Materials Science Seminar
"Microscopic engineering of complex oxide ground states"
Presented by Derek Meyers, University of Arkansas
Monday, June 29, 2015, 1:30 pm
ISB Bldg. 734, Conf. Rm. 201 (upstairs)
Hosted by: Mark Dean
Transition metal oxides have come to the forefront of condensed matter research in the past several decades due to their highly diverse phase space and remarkable susceptibility to external tuning. This has lead to their prevalence in the pursuit of designer phases, i.e. room temperature superconductivity, topological phases, and etc. In this talk we explore several methods for engineering the ground state of these systems including "ordered doping", applied epitaxial strain, and superlattice heterostructuring in an effort to gain further insight into the microscopic origin of this tunability. We employ synchrotron based xray spectroscopy and resonant diffraction to elucidate the explicit origin of the observed anomalous behaviors. In particular, our results reveal the ability to mask the effects of spinorbit coupling in heavier oxides and to suppress or enhance bulk phase transitions by design.
Nuclear Theory/RIKEN Seminar
"Event by Event fluctuations in pQCD + saturation + hydro model: pinning down QCD matter shear viscosity in AA collisions"
Presented by Risto Paatelainen, University of Jyvaskyla
Friday, June 26, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
We introduce an eventbyevent perturbativeQCD + saturation + hydro ("EKRT") framework for ultrarelativistic heavyion collisions, where we compute the produced fluctuating QCDmatter energy densities from nexttoleading order perturbative QCD using a saturation conjecture to control soft particle production, and describe the spacetime evolution of the QCD matter with dissipative fluid dynamics, event by event. We perform a simultaneous comparison of the centrality dependence of hadronic multiplicities, transverse momentum spectra, and flow coefficients of the azimuthangle asymmetries, against the LHC and RHIC measurements. We compare also the computed eventbyevent probability distributions of relative fluctuations of elliptic flow, and eventplane angle correlations, with the experimental data from Pb+Pb collisions at the LHC. We show how such a systematic multienergy and multiobservable analysis tests the initial state calculation and the applicability region of hydrodynamics, and in particular how it constrains the temperature dependence of the shear viscositytoentropy ratio of QCD matter in its different phases in a remarkably consistent manner.
RIKEN Lunch Seminar
"OneFlavor QCD and the Dirac Spectrum at $\theta=0$"
Presented by Jacobus Verbaarschot, Stony Brook University
Thursday, June 25, 2015, 12:30 pm
Building 510 Room 2160
Hosted by: Daniel Pitonyak
The chiral condensate of oneflavor QCD is continuous when the quark mass crosses zero. In the sector of fixed topological charge though, the chiral condensate becomes discontinuous at zero mass in the the thermodynamical limit. To reconcile these contradictory observations, we have evaluated the spectral density of the Dirac operator in the epsilon domain of oneflavor QCD. In this domain, we have obtained exact analytical expressions which show that the spectral density at $\theta = 0$ becomes a strongly oscillating function for negative quark mass with an amplitude that increases exponentially with the volume. As is the case for QCD at nonzero chemical potential, these strong oscillations invalidate the BanksCasher formula and result in a chiral condensate that is continuous as a function of the quark mass. An additional subtlety is the effect of the topological zero modes which will be discussed as well.
Nuclear Theory/RIKEN seminar
"Jet angular broadening in HeavyIon collisions"
Presented by Yacine MehtarTani, University of Washington
Friday, June 19, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
The advent of the LHC opened up new perspectives for jetquenching physics. For the first time, high enough energies are reached in heavyion experiments to produced jets in large numbers, and the unprecedented detector capabilities of ALICE, ATLAS and CMS, not only extend the kinematic range for the measurements previously performed at RHIC, but also allow to explore a variety of new jetquenching observables. In this talk, I address the question of the angular broadening of jets in the presence of a dense QCD matter. I start by discussing the fundamental mechanisms underlying the formation of gluon cascades induced by multiple interactions of high energy jets with the quarkgluon plasma. Then, the rate equation that describes the evolution of the energy and angular distribution of the inmedium gluon shower is presented and solved. Two remarkable phenomena emerge. First and foremost the energy spectrum (of jet constituents) exhibits a scaling behavior characterized by a constant flow of energy towards low momenta akin to wave turbulence. As a result, energy is rapidly transported from the energy containing partons to low momentum gluons before it dissipates into the medium. Second, mediuminduced gluon cascades develop and transport energy at parametrically large angles with respect to the jet axis. This picture is in semiquantitive agreement with a recent CMS analysis of the missing energy in asymmetric dijet events where the energy balance is recovered at large angles and very soft particles.
PubSci
"Big Bang Physics and the Building Blocks of Matter"
Thursday, June 18, 2015, 7 pm
The Bahche 191 7th St, Brooklyn, NY 11215
Invite your friends and colleagues to a lively discussion for the scienceinterested (or just plain curious) and chat with scientists in an informal and friendly way. No stuffy lectures â€" just a dynamic talk with a diverse audience and a lot of good cheer. Physicists who work at Brookhaven's particle collider will talk about how they explore what happened at the dawn of time from a Lab on Long Island. How did the Universe take shape? What binds matter together? How do we answer those questions?
Particle Physics Seminar
"Detection of Lensing of the CMB by Dark Matter Halos"
Presented by Mathew S Madhavacheril, Stony Brook University
Thursday, June 18, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Morgan May
I will report on the first detection of lensing of the cosmic microwave background by dark matter halos. Halo lensing of the CMB provides a method for constraining cluster masses complementary to optical weak lensing, with the advantage that the source plane has a very well determined redshift and statistical properties. In this work, the lensing field was reconstructed from CMB temperature observations using the ACTPol telescope and stacked at the location of CMASS galaxies which trace dark matter halos of ~10^13 M_solar galaxy groups, providing a 3.2 sigma detection and a ~35% mass constraint. I will also briefly touch on the capabilities of future CMB experiments to use this method to constrain dark energy parameters.
RIKEN Lunch Seminar
"Selfsimilar evolution for inverse cascade of magnetic helicity driven by the chiral anomaly"
Presented by Yi Yin, Brookhaven National Laboratory
Thursday, June 18, 2015, 12:30 pm
Small Seminar Room, Bldg. 510
Hosted by: Daniel Pitonyak
We show by solving Maxwell's equations in the presence of chiral magnetic current that the chiral anomaly would induce the inverse cascade of magnetic helicity. We found at late time, the evolution of magnetic helicity spectrum is selfsimilar and axial charge decays as a power law in time. We visualize how a linked magnetic configuration would evolve into a knotted configuration in real space during such evolution.
Particle Physics Seminar
"Constraining the Standard Model and new physics with LHC data"
Presented by Alessandro Tricoli, CERN
Friday, June 12, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Ketevi Assamagan
The Large Hadron Collider (LHC) project at CERN Laboratory in Geneva has achieved one of its primary goals, i.e. the discovery of the Higgs boson particle, which completes the Standard Model of particle physics. However, no signatures of new physics beyond the Standard Model have been observed yet, despite thorough searches. Nature turns out to be subtle. The direct search will continue in the upcoming LHC runs, however new physics can also be pursued indirectly by looking for deviations of experimental results from predictions in measurements of Standard Model processes. The LHC has provided a large data set during its first years of operations. This has been used to perform measurements of Standard Model processes that constrain predictions in the strong and electroweak sectors and are sensitive to new physics in a modelindependent way, thanks to the high level of precision and the extent of their kinematic reach. A good understanding of these processes is of paramount importance for precision Higgs physics, as well as for searches for new physics, as they constitute irreducible backgrounds. After presenting a selection of highlights of recent Standard Model measurements from the LHC, I will discuss how the precision and phase space reach of these measurements will improve in future LHC runs, given the increase of centreofmass energy and integrated luminosity, emphasising some of the experimental challenges ahead.
Particle Physics Seminar
"Search for dark sector particles at Belle and Belle II"
Presented by Igal Jaegle, University of Hawai`i at MÄnoa
Thursday, June 11, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Ketevi A. Assamagan
The dark photon, Aâ€²,, and the dark Higgs boson, hâ€², are hypothetical constituents featured in a number of recently proposed Dark Sector Models. We will present a search for these particles in the socalled Higgsstrahlung channel, e+eâˆ'â†'Aâ€²hâ€², with hâ€²â†'Aâ€²Aâ€². We investigated ten exclusive finalstates with Aâ€²â†'e+eâˆ', Î¼+Î¼âˆ', or Ï€+Ï€âˆ', in the mass ranges 0.1 GeV/c2 <mAâ€²<3.5 GeV/c2 and 0.2 GeV/c2 <mhâ€²<10.5 GeV/c2. We also investigated three inclusive finalstates, 2(e+eâˆ')X, 2(Î¼+Î¼âˆ')X, and (e+eâˆ')(Î¼+Î¼âˆ')X, where X denotes a dark photon candidate detected via missing mass, in the mass ranges 1.1 GeV/c2 <mAâ€²<3.5 GeV/c2 and 2.2 GeV/c2 <mhâ€²<10.5 GeV/c2. Using the entire 977fbâˆ'1 data set collected by Belle, we observed no significant signal. We will also discuss prospects for searches for light dark matter and the dark photon in the radiative decay process at Belle and Belle II.
HET/RIKEN seminar
"New physics in b—>s transitions after LHC run 1"
Presented by Wolfgang Altmannshofer, Perimeter Institute
Wednesday, June 10, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: ChienYi Chen
I will discuss interpretations of the recent updated angular analysis of the B>K*mu+mu decay by the LHCb collaboration. A global fit to all relevant measurements probing the flavor changing neutral current b>s mu mu transition shows tensions with Standard Model expectations. Assuming hadronic uncertainties are estimated in a sufficiently conservative way, I will discuss the implications of the experimental results on new physics, both model independently as well as in the context of models with flavor changing Z' bosons.
Nuclear Theory/RIKEN seminar
"Novel mechanisms of charmonium suppression/enhancement in pA and AA collisions"
Presented by Boris Kopeliovich, Universidad Tecnica Federico Santa Maria, Valparaiso
Friday, June 5, 2015, 2 pm
Small Seminar Room, Bldg. 510
Hosted by: Soeren Schlichting
Charmonium production in pA collisions is known to be suppressed by shadowing and absorption. There are however nuclear effects, which enhance charmonium yield. They steeply rise with energy and seem to show up in LHC data for J/psi production in pA collisions. In the case of heavy ion collisions produced charmonia are additionally suppressed by final state interaction in the created dense medium. On the contrary to current evaluations of the melting effects caused by Debye screening, a charmonium produced with a large pT easily survives even at high temperatures. Another source of charmonium suppression, missed in previous calculations, colorexchange interactions with the medium, leads to suppression of a comparable magnitude. A quantitative comparison is performed.
CondensedMatter Physics & Materials Science Seminar
"GGE and applications for integrable models"
Presented by Garry Goldstein, Rutgers University
Thursday, June 4, 2015, 4 pm
ISB 2nd floor seminar room
Hosted by: Robert Konik
We consider quenches of integrable models. We derive a Yudson representation applicable to finite sized systems. Using this representation we find expressions for the time dependence of density density and related correlation functions for an arbitrary quench of the repulsive LiebLiniger gas. We use this to show that the GGE formalism is applicable to the long time limit for quenches of the LiebLiniger gas with sufficiently regular initial states. We then show that no similar GGE formalism applies to quenches for integrable models with bound states (such as the XXZ model or the Hubbard model). We study several specific examples of quenches, in particular quenches where the initial state is a Mott insulator or has low entropy. We find the exact quasiparticle density for such quenches and use it to study the long time limit of some correlation functions for the system. We also consider quenches of confined systems, in particular the Lieblinger gas in a box. We show that the GGE formalism applies to the long time average of such quenches. We use this observation to compute the long time average quasiparticle density for some quenches similar to the Quantum Newton's cradle quench experiment. We also compute various correlation functions for the system in particular the probability distribution for the particle velocity.
CondensedMatter Physics & Materials Science Seminar
"Band edge and photo induced superconductivity"
Presented by Garry Goldstein, Rutgers
Thursday, June 4, 2015, 1:30 pm
2nd Fl Lecture Room ISB
Hosted by: Robert Konik
We discuss novel routes to obtain superconductivity in semiconductors. We consider a semiconductor with a band dispersion where there is a band edge, such as semiconductors with Rashba spinorbit coupling or bilayer graphene with a voltage between the layers. We find robust superconductivity, both pwave and swave depending on the type of band edge, for semiconductors with attractive interactions (such as those caused by phonon exchange) when we tune the chemical potential close to the band edge. We also consider photo induced superconductivity in a two band semiconductor. We use optical pumping to induce nonequilibrium populations within the bands. We find robust superconductivity for appropriate chemical potential and dispersion relations for the bands. This swave superconductivity can be induced by both repulsive and attractive interactions depending on the exact band dispersions. Various band geometries are discussed.
Physics Colloquium
"Quarkonium with Effective field theories"
Presented by Nora Brambilla, Munich Technical University
Tuesday, June 2, 2015, 3:30 pm
Large Seminar Room, Bldg. 510
Hosted by: Peter Petreczky
Quantum Chromodynamics (QCD) is the sector of the Standard Model of particle physics that describes the strong interaction, deceptively simple to formulate but notoriously difficult to solve. Heavy quarkonium is a multiscale system that probes the different energy regimes of QCD, from the highenergy region, where an expansion in the coupling constant is possible and precision studies may be done, to the lowenergy region, dominated by confinement and the many manifestations of the nonperturbative strong dynamics. Properties of production and absorption of quarkonium in a medium are also crucial for the study of QCD at high density and temperature. On the theoretical side, the construction of new nonrelativistic effective field theories for quarkonium has recently revolutionized the field providing both a conceptual framework and a powerful calculational tool. On the experimental side, the diversity, quantity and accuracy of the data collected in the last few years at B and taucharm factories and at RHIC and LHC experiments is impressive, featuring the observation of new states and new unexpected processes. I will discuss these theoretical and experimental advancements and their implications for our understanding of strong interactions.
Nuclear Physics Seminar
"Elliptic flow from anisotropic escape"
Presented by Denes Molnar, Purdue University
Tuesday, June 2, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Jin Huang
While hydrodynamics is regarded as the dominant paradigm for describing heavyion collisions at RHIC and LHC energies, its applicability to nuclear reactions is not very well understood. Open question remain about the mechanism of rapid thermalization, initial conditions, treatment of decoupling (conversion of the fluid to particles), finite system effects, and quantum corrections in very small systems, for example. In a recent work (arXiv:1502.05572) we showed that in the AMPT transport model elliptic flow is generated quite differently from hydrodynamics, mainly through anisotropic escape from the collision zone. I will demonstrate that this is, in fact, a general feature of kinetic theory, originating in the modest opacities <Ncoll> \sim 45 in AMPT calculations. Implications of the escape effect will be discussed together with connections to other hydro related problems such as proper particle distributions (arXiv:1404.8750) and anisotropic flow from quantum mechanics (arXiv:1404.4119).
Particle Physics Seminar
"LHCb Run I Results and Run II Prospects"
Presented by Philip Ilten, Massachusetts Institute of Technology
Thursday, May 28, 2015, 3 pm
Small Seminar Room, Bldg. 510
Hosted by: Ketevi A. Assamagan
The LHCb detector is a forward arm spectrometer on the Large Hadron Collider, designed for the study of particles containing b or c quarks. A variety of recent results from the Run I dataset, taken from 2010  2013, will be presented, emphasizing the scope of the LHCb physics program. These areas include central exlusive production of quarkonia, exotic particle searches, precision electroweak crosssections, CKM measurements, and more. Prospects for Run II measurements will be outlined.
CondensedMatter Physics & Materials Science Seminar
"Transport properties of novel thermoelectric materials"
Presented by Hang Chi, Department of Physics, University of Michigan
Thursday, May 28, 2015, 11 am
Bldg.480 Conf. Rm
Hosted by: Qiang Li
Thermoelectric materials can recover waste industrial heat and convert it to electricity as well as provide efficient local cooling of electronic devices. The efficiency (determined by the dimensionless figureofmerit ZT) of such environmentally responsible and exceptionally reliable solid state energy conversion can be enhanced through (i) electronic band engineering (ntype Mg2SiMg2Sn solid solutions and ptype SnTe) and (ii) thermal conductivity reduction (Ge/Te double substituted CoSb3). Detailed transport and structure studies of Bi2Te3based single crystals demonstrate that a bulk (semi)insulating state for such a topological insulator can be achieved via group III (Tl or In) elemental doping, which opens an avenue for further investigations of transport phenomena related to surface states. Further systematic study in Bi2Te3based molecular beam epitaxial (MBE) thin films grown on sapphire (0001) and/or BaF2 (111) substrates, reveal that the peak of phonon drag can be tuned by the choice of substrates with different Debye temperatures.
Nuclear Physics Seminar
"Probing Nucleon Structure Through Transversely Polarized Protonproton Collisions at STAR"
Presented by Jim L. Drachenberg, Valparaiso University
Tuesday, May 26, 2015, 11 am
Small Seminar Room, Bldg. 510
Hosted by: Oleg Eyser
At leading twist, a complete picture of the onedimensional momentum structure of the nucleon requires knowledge of three types of parton distribution functions (PDFs): the unpolarized PDFs; the helicity PDFs; and the transversity PDF, related to the transverse polarization of quarks within a transversely polarized nucleon. Current global extractions of transversity are limited by the kinematic reach of existing semiinclusive deepinelastic scattering (SIDIS) experiments. Beyond the open questions of onedimensional nucleon structure, myriad opportunities abound in exploring the multidimensional structure of the nucleon. A step toward this goal is to investigate the nature of the transverse momentum dependence (TMD) of nucleon parton densities and their relation to nucleon spin polarization. The STAR experiment at RHIC proposes to investigate these and other spinrelated phenomena through the interaction of highenergy collisions between spinpolarized protons. In preliminary results from data collected in 2011 at $\sqrt{s}=500$ GeV and in 2012 at $\sqrt{s}=200$ GeV, STAR has observed the first nonzero spin asymmetries due to the effects of transversity in protonproton collisions. Studying these effects through both jet+hadron and dihadron production channels and across a range of collision energy yields the potential not only to extend understanding of transversity beyond the current kinematic reach but also to address longstanding theoretical questions concerning the universality and evolution of transversity and polarized fragmentation functions. From the 2011 dataset STAR has also released the first preliminary measurements sensitive to the Sivers TMD PDF in weakboson production. Weak boson production provides an ideal tool for isolating the unconstrained seaquark Sivers PDF and may provide sensitivity to the expected modified universality of the Sivers PDF when compared to SIDIS. These exploratory measurements pave the way for future higher precision inv
Currently showing events from the past year. See all past events »