Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session CF: Proton Structure |
Hide Abstracts |
Chair: Paul Reimer, Argonne National Laboratory Room: Pavilion Ballroom A |
Friday, October 14, 2016 8:30AM - 8:42AM |
CF.00001: Drell-Yan Angular Distributions at the E906 SeaQuest Experiment David Kleinjan Measurement of Drell-Yan angular distributions in the Collins-Soper frame provide a unique study of QCD. Previous experimental results showed a violation of the Lam-Tung relation (1 – $\lambda$ $\neq$ 2$\nu$). This violation could be described by a range of non-perturbative effects, including the naive T-odd Boer-Mulders TMD, which describes spin-momentum correlations in the nucleon. Presently, E906/SeaQuest experiment at Fermilab can measure Drell-Yan dimuon pairs produced from a 120 GeV unpolarized proton beam directed on various nuclear targets. The Drell-Yan angular distributions will be measured at higher-x than previous experiments, further disentangling the role the Boer-Mulders TMD and other non-perturbative effects play in the structure of the nucleon. [Preview Abstract] |
Friday, October 14, 2016 8:42AM - 8:54AM |
CF.00002: ABSTRACT WITHDRAWN |
Friday, October 14, 2016 8:54AM - 9:06AM |
CF.00003: Drell-Yan with a polarized target and SeaQuest Andi Klein We will discuss the new E1039 experiment at Fermilab to measure the single spin asymmetry of the Drell-Yan process on a transversely polarized target. This measurement can be used to determine the sign and magnitude of the Sivers asymmetry. A non-vanishing Sivers asymmetry requires a non-zero orbital angular momentum contribution of the sea quarks to the nucleon spin. This will be the first ever measurement of the Sivers asymmetry for the $\bar{u}$ quark. The experiment will be a continuation of the current unpolarized SeaQuest program at Fermilab. [Preview Abstract] |
Friday, October 14, 2016 9:06AM - 9:18AM |
CF.00004: Measurement of Drell-Yan longitudinal double spin asymmetry in polarized p + p collisions at PHENIX Gonaduwage Perera, Stephen Pate Measurement of the longitudinal double spin asymmetry ($A_{LL}$) in the Drell-Yan process in high energy polarized proton-proton collisions provides clean access to the anti-quark helicity distributions in the proton without involving quark fragmentation functions. In the PHENIX experiment at RHIC, the Forward Silicon Vertex Detector (FVTX) together with the forward muon spectrometers have been used to study the Drell-Yan process by detecting the muon pairs in the forward region (1.2 $< \eta <$ 2.4). In this talk, the status of evaluating the Drell-Yan signal fraction and the $A_{LL}$ asymmetry in the intermediate mass region (4.5 GeV $< M <$ 8 GeV) using the RHIC 2013 dataset of proton-proton collisions at a center of mass energy of 510 GeV are presented. [Preview Abstract] |
Friday, October 14, 2016 9:18AM - 9:30AM |
CF.00005: Measurement of the parity-violating longitudinal single-spin asymmetry $A_{L}$ for $W^{-(+)}$ boson production in polarized proton collisions at $\sqrt{s}=510$ GeV at RHIC Bernd Surrow The STAR experiment at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is carrying out a spin physics program in high-energy polarized proton collisions to gain a deeper insight into the spin structure and dynamics of the proton. The collision of polarized protons at $\sqrt{s}=500\,$GeV opened a new era of spin-flavor structure studies using the production of $W^{-(+)}$ bosons which are primarily produced in $\bar{u}+d\,(\bar{d}+u)$ collisions. The STAR experiment is well equipped to measure $W^{-(+)} \rightarrow e^{-}+ \bar{\nu}_{e}\,(e^{+}+ \nu_{e})$ in longitudinally polarized proton collisions. The published STAR $A_L$ results (combination of 2011 and 2012 data) have been used by two global analyses groups suggesting a significant impact in constraining the helicity distributions of anti-$u$ and anti-$d$ quarks. In 2013, the STAR experiment collected a data set at $\sqrt{s}=510$ GeV with a factor of three larger figure of merit based on a total integrated luminosity of $\sim$300 pb$^{-1}$ and an average beam polarization of $\sim$54\%. We will report on the status of the STAR 2013 W $A_L$ analysis along with future plans. [Preview Abstract] |
Friday, October 14, 2016 9:30AM - 9:42AM |
CF.00006: Transverse double-spin asymmetries for electroweak gauge-boson production in high-energy polarized $\vec{p}+\vec{p}$ collisions Bernd Surrow, Jacques Soffer, Claude Bourrely The collision of high-energy polarized proton beams at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory provides a powerful way to gain a deeper insight into the spin structure and dynamics of the proton such as the study of the helicity distributions of gluons and quarks / antiquarks based on well established high-energy QCD and $W$ boson processes, respectively. Several studies have been suggested in the past to gain a better understanding of the transversity distribution, in particular the measurement of the transverse double-spin asymmetries ($A_{TT}$) for Drell-Yan production. Prior NLO calculations for Drell-Yan $\gamma / Z$ exchange have been used to evaluate $A_{TT}$ for $Z$ production using maximal bounds for the transversity distribution. The transverse double-spin asymmetry for $W$ production is expected to be zero. The status of $A_{TT}$ NLO calculations specifically for $\gamma / Z$ exchange will be discussed using maximal bounds of transversity distributions within the framework by Bourrely and Soffer. [Preview Abstract] |
Friday, October 14, 2016 9:42AM - 9:54AM |
CF.00007: Longitudinal Double-Spin Asymmetries for Forward Di-jet Production in Polarized $pp$ Collisions at $\sqrt{s}$ = 200 GeV Ting Lin One of the primary goals of the STAR spin program is to determine the spin-dependent gluon distribution, $\Delta$G, of the proton. Recent measurements of the longitudinal double-helicity asymmetry, $A_{LL}$, from inclusive jets place strong constraints on $\Delta$G and, for the first time, find evidence for non-zero gluon polarization values for partonic momentum fraction $x$ greater than 0.05. In contrast to inclusive jets, di-jet correlation measurements provide access to partonic kinematics, at leading order, and thus give better constraints on the behavior of $\Delta g(x)$ as a function of gluon momentum fraction. Furthermore, di-jet measurements at forward rapidity probe the lower $x$ values where contributions to $\Delta$G are poorly constrained. Preliminary $A_{LL}$ results for di-jets with $-0.8 < \eta_1 < 0.8$ and $0.8 < \eta_2 < 1.8$, from proton+proton collisions at $\sqrt{s}$ = 200 GeV recorded in 2009, will be presented. [Preview Abstract] |
Friday, October 14, 2016 9:54AM - 10:06AM |
CF.00008: Double-Spin Asymmetry in Neutral Pion Production at Intermediate Pseudorapidity in Longitudinally Polarized $p+p$ Collisions in the STAR Detector at RHIC Adam Gibson One of the outstanding problems in nuclear physics is to explain the helicity of the proton in terms of its constituents. It has long been known that the helicity of the quarks is insufficient, initially a puzzling result. In recent years it has become clear that the gluon plays an important role, but the uncertainty on the contribution from low $x$ gluons in particular has remained large. The STAR and PHENIX detectors at RHIC have been critical in illuminating the role of the gluon. STAR published an analysis of neutral pions in the intermediate pseudorapidity Endcap Electromagnetic Calorimeter (EEMC, 1.09 $< \eta < $ 2.00) using a dataset from 2006 at $\sqrt{s} = 200$ GeV that was complimentary to results using jets and pions at mid-rapidity and at forward pseudorapidites. Our present analysis extends that earlier EEMC result using a much larger dataset in the EEMC at $\sqrt{s} = 510$ GeV, extending the reach of the analysis to lower gluon $x$. We will present the status of this analysis of the double-spin asymmetry in neutral pion production in longitudinally polarized $p+p$ collisions in the STAR detector at RHIC ($\pi^0$ $A_{LL}$), and discuss prospects for the future. [Preview Abstract] |
Friday, October 14, 2016 10:06AM - 10:18AM |
CF.00009: The RHIC Cold QCD Plan for 2017 to 2023: A Portal to the EIC Renee Fatemi In light of the recent recommendation by the Nuclear Science Advisory committee to construct a U.S. based Electron Ion Collider (EIC), the spin community at the Relativistic Heavy Ion Collider has developed a program of must-do experiments to be run during the period leading up to the turn on of the EIC. These experiments will utilize the unique capabilities of the world's only polarized proton-proton collider to make measurements that will, when combined with data from the EIC, test the limits and validity of factorization and universality. This program includes measurements of observables that are sensitive to the universality and evolution of initial and final state transverse momentum distributions, the transversity distributions at high x and gluon fragmentation functions. The timeline and detector requirements for implementation will be discussed. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700