Bulletin of the American Physical Society
2012 Fall Meeting of the APS Division of Nuclear Physics
Volume 57, Number 9
Wednesday–Saturday, October 24–27, 2012; Newport Beach, California
Session JC: Hadron Physics IV |
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Chair: Carlos Granados, Thomas Jefferson National Accelerator Facility Room: Plaza III |
Friday, October 26, 2012 10:30AM - 10:42AM |
JC.00001: Clarifying the Structure of the Nucleon: Status of the SeaQuest Experiment (Fermilab E906) Larry Donald Isenhower SeaQuest (Fermilab E906) started commissioning and data collection in March and April of this year. SeaQuest will make a number of measurements in kinematic ranges with a precision that have not been possible in any previous experiment. The experiment uses the Drell-Yan process to probe the light antiquark sea and follows up on measurements of Fermilab E866/NuSea, with a goal of answering important questions raised by that experiment. One is to determine the ratio of the anti-down to anti-up quarks in the nucleon at high Bjorken x. Above x=0.25, NuSea data indicate this ratio could be changing in a surprising manner where the ratio could be dipping below one. This is just one of several determinations SeaQuest will make. A brief description of other physics to be addressed by SeaQuest will be followed by the present status of the experiment as it prepares to start up next spring when the Fermilab MI resumes operation. In the very short commissioning run we were able to validate that the detector and DAQ systems all function. These data are being used to improve the implementation of the analysis chain and guide upgrades of the SeaQuest systems for high intensity running. It is expected that the experiment will be running at full intensity in 2013. [Preview Abstract] |
Friday, October 26, 2012 10:42AM - 10:54AM |
JC.00002: Exploring Light Anti-quark Asymmetry with the SeaQuest Experiment Zhongming Qu The Fermilab E906/SeaQuest experiment measures the anti-quark structure of the nucleon which eventually will give unique insight into the origin of the sea quarks. The predecessor E866/NuSea experiment showed a clear asymmetry of the ratio for Bjorken x$<$0.2 while it approaches unity for x$>$0.25, indicating clear deviations from the phenomenological models. The E906/SeaQuest experiment will measure the Drell-Yan cross section in p-p and p-d scattering and will determine the $ {\bar{d}}/{\bar{u}}$ asymmetry over 0.04$<$x$<$0.45, thus extending the available E866 measurements to a higher x region. The experiment has finished taking commissioning data in May 2012 using liquid hydrogen and deuterium targets. It will resume taking data in early 2013. The 120GeV beam extracted from the Fermilab Main Injector increases the event rate by factor of 50 compared to E866. This will significantly improve the statistics during the expected two-year run from early 2013 to Dec 2014. The scientific motivation as well as the current status, primarily the design, performance, and the future improvements of the current cryogenic targets will be presented. The expected results from E906/SeaQuest experiment will also be addressed. [Preview Abstract] |
Friday, October 26, 2012 10:54AM - 11:06AM |
JC.00003: Putting a New Spin on an Existing Machine: Prospects for Polarizing the Fermilab Main Injector Christine Aidala As we continue to explore quantum chromodynamics (QCD) as the theory of the strong force, with gluon interactions in hadrons responsible for more than 98\% of the visible mass in the universe, spin remains an important degree of freedom to be able to manipulate in order to advance the field. In particular, spin-momentum correlations in QCD, broadly analogous to quantum electrodynamical spin-orbit couplings in the hydrogen atom, have risen to the forefront of QCD research over the past decade. The current status of a proposal to polarize the proton beam at the Fermilab Main Injector will be presented, and the physics that could be accomplished with a hadronic fixed-target program at such a facility will be discussed. [Preview Abstract] |
Friday, October 26, 2012 11:06AM - 11:18AM |
JC.00004: Elastic pp Scattering at LHC Energies in Various Multi-Pomeron Exchange Models Ivan Novikov, Yuli Shabelski We consider the data for elastic pp scattering in the framework of Regge theory in various models of multiple Pomeron exchanges: quasi-eikonal approach and two-channel approach. The results of the model calculations are compared with the experimental data presented by the TOTEM collaboration. [Preview Abstract] |
Friday, October 26, 2012 11:18AM - 11:30AM |
JC.00005: Pion Parton Distribution Function from DSE-QCD Moments Konstantin Khitrin, Javier Cobos-Martinez, Craig Roberts, Peter Tandy We obtain the valence quark PDF of the pion from a direct formulation of the moments within a Euclidean-formated modeling of QCD. There are no limitations on the number of moments that can be obtained. This approach employs the ladder-rainbow (LR) truncation of the Dyson-Schwinger equation (DSE) formulation of QCD and eliminates an obstacle that hinders a direct approach to the PDF. Bethe-Salpeter wavefunctions and dressed quark propagators from previous extensive DSE-LR work are recast in a form that allows exact Feynman integral techniques. Performance of this approach will be assessed through results for the reconstructed PDF, and considerations of the momentum sum rule. [Preview Abstract] |
Friday, October 26, 2012 11:30AM - 11:42AM |
JC.00006: Prospects of polarized Drell-Yan experiments Kwangbok Lee, Xiaodong Jiang Drell-Yan spin observable measurements with polarized proton (and/or $^3$He) beams provide valuable and unique probes to access the fundamental structure of nucleons. For example, comparing to Semi-Inclusive Deep Inelastic Scattering (SIDIS), double longitudinal spin asymmetries in Drell-Yan reactions provide a clean access to anti-quark helicity distributions without involving quark fragmentation functions. Transverse Single Spin Asymmetry (SSA) in Drell-Yan reactions can test the predicted sign change of quark Sivers function compared to that from SIDIS measurement, providing an important test of the fundamental QCD as well as our current understanding of the transverse spin phenomena. Drell-Yan SSA can also access other quark Transverse Momentum Dependent distributions (TMDs), for example, quark's transversity ($h_1$), and quark's ``longitudinal helicity'' ($h_{1L}^\perp$). We will review several proposed options of polarized beams, such as Fermilab's Main Injector, J-PARC and RHIC and will discuss the prospects and physics sensitivities of double-spin and single-spin Drell-Yan observable measurements through detailed Monte Carlo simulations. [Preview Abstract] |
Friday, October 26, 2012 11:42AM - 11:54AM |
JC.00007: Sivers Asymmetries in Polarized Drell-Yan Production of Muon Pairs at COMPASS IhnJea Choi The COMPASS experiment is a fixed target experiment located at the M2 beam line of the CERN SPS, which provides muon and hadron beams for the investigation of longitudinal and transverse spin structure of the nucleon and hadron spectroscopy. Recently, a new proposal of the COMPASS collaboration has been accepted at CERN. A main objective of the COMPASS II proposal is to probe transverse momentum dependent (TMD) parton distributions of the nucleon through the Drell-Yan process with negative poion beams incident on polarized proton targets. The measurement of Sivers asymmetries in Drell-Yan production of muon pairs will test the predicted sign change of Sivers single spin asymmetries between semi inclusive scattering experiments with lepton beams on polarized targets and the Drell-Yan process with hadron beam and target. In this presentation we will discuss the physics motivation of the COMPASS II Drell-Yan measurement, present sensitivity projections and discuss the status of the absorber and spectrometer underway for the proposed Drell-Yan measurement. [Preview Abstract] |
Friday, October 26, 2012 11:54AM - 12:06PM |
JC.00008: ABSTRACT WITHDRAWN |
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