Nuclear Physics Seminar

"Recent STAR SPIN results I"

Presented by Zhanwen Zhu and Maria Zurek, Shandong University/Lawrence Berkeley National Laboratory

Tuesday, June 23, 2020, 11:00 am — Webcast

Measurement of transverse single spin asymmetries at forward rapidities by the STAR experiment at √s = 200 and 500 GeV Zhanwen Zhu, Shandong University We present recent results of transverse single spin asymmetries (TSSA) for neutral pions using the Forward Meson Spectrometer at STAR at center of mass energies of 200 and 500 GeV in proton-proton collision. In order to separate the contribution of initial and final state effects at both energies, we also measured for the electromagnetic jet TSSA and the Collins asymmetry for neutral pions inside the electromagnetic jet. These results together provide rich information to understand the origin of neutral pion TSSA. Longitudinal double-spin asymmetries for inclusive jets produced in √s = 200 GeV proton-proton collisions Maria Zurek, Lawrence Berkeley National Laboratory STAR measures double-spin asymmetries ALL in longitudinally polarized proton-proton collisions to determine the gluon helicity distribution ?G(x,Q2). Previously published inclusive jet results based on √s = 200 GeV data collected in 2009 provided first evidence for positive gluon polarization for a momentum fraction x > 0.05 at a hard perturbative scale Q2 = 10 GeV2. This talk will present new preliminary results from 2015 data with an approximately twice larger figure of merit and correspondingly better precision.

Hosted by: Rongrong Ma

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