Measurement of parity-violating spin asymmetries in W ± production at midrapidity in longitudinally polarized p +p collisions

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Abstract

We present midrapidity measurements from the PHENIX experiment of large parity-violating single-spin asymmetries of high transverse momentum electrons and positrons from W±/Z decays, produced in longitudinally polarized p+p collisions at center of mass energies of s=500 and 510 GeV. These asymmetries allow direct access to the antiquark polarized parton distribution functions due to the parity-violating nature of the W-boson coupling to quarks and antiquarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb-1, which exceeds previous PHENIX published results by a factor of more than 27. These high Q2 data probe the parton structure of the proton at W mass scale and provide an important addition to our understanding of the antiquark parton helicity distribution functions at an intermediate Bjorken x value of roughly MW/s=0.16.

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Authors
Organisations
External organisations
  • University of Colorado
  • Los Alamos National Laboratory
  • University of Michigan
  • Stony Brook University
  • RIKEN SPring-8 center
  • Riken BNL Research Center
  • University of Tokyo
  • Howard University
  • High Energy Accelerator Research Organization, Tsukuba
  • Iowa State University
  • Kyoto University
  • Brookhaven National Laboratory
  • Oak Ridge National Laboratory
  • Institute for High Energy Physics, Russia
  • University of Massachusetts
  • University of California, Riverside
  • University of New Mexico
  • Baruch College
  • Petersburg Nuclear Physics Institute (PNPI)
  • Vanderbilt University
  • St. Petersburg State Polytechnical University
  • Russian Research Center 'Kurchatov Institute'
  • New Mexico State University
  • Columbia University
  • University of Illinois at Urbana-Champaign
  • Seoul National University
  • Bhabha Atomic Research Centre
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Subatomic Physics
Original languageEnglish
Article number051103
JournalPhysical Review D
Volume93
Issue number5
Publication statusPublished - 2016 Mar 23
Publication categoryResearch
Peer-reviewedYes