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W Production in Polarized p-p Collisions: A Probe for Sea Quark Spin

W Production in Polarized p-p Collisions: A Probe for Sea Quark Spin. Daniel Jumper University of Illinois Urbana-Champaign For the PHENIX Collaboration DNP Meeting - October 25 th , 2012. Outline. Proton Spin Structure W Asymmetry Measurement PHENIX and RHIC Analysis and Initial Results

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W Production in Polarized p-p Collisions: A Probe for Sea Quark Spin

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  1. W Production in Polarized p-p Collisions: A Probe for Sea Quark Spin Daniel Jumper University of Illinois Urbana-Champaign For the PHENIX Collaboration DNP Meeting - October 25th, 2012

  2. Daniel Jumper - DNP 2012 Outline • Proton Spin Structure • W Asymmetry Measurement • PHENIX and RHIC • Analysis and Initial Results • 2013 Run Projections

  3. Daniel Jumper - DNP 2012 Proton Spin Structure • Contributions to proton spin: • 20 years of DIS/SIDIS measurements • DIS: Sensitive to quark antiquark sum • SIDIS: Limited precision • Recent work: pp collisions at RHIC Phys. Rev. D 80, 034030 (2009)

  4. Daniel Jumper - DNP 2012 Proton Spin Structure • Contributions to proton spin: • 20 years of DIS/SIDIS measurements • DIS: Sensitive to quark antiquark sum • SIDIS: Limited precision • Recent work: pp collisions at RHIC • Our measurement focuses on , specifically and Phys. Rev. D 80, 034030 (2009)

  5. Daniel Jumper - DNP 2012 Sea Quark Spin: Using the Weak Interaction • Study single spin asymmetry in production cross section of W bosons in polarized pp collisions at =500 GeV • Polarized proton beams with different possible longitudinal polarization orientations • W produced in Quark-antiquark annihilation decays into lepton/neutrino. • Advantages: • High (lower NLO sensitivity) • No dependence on fragmentation functions • More direct flavor and antiquark sensitivity

  6. Daniel Jumper - DNP 2012 Single Spin Asymmetry in W Boson Production • Observe W decay at forward rapidity • Leading Order picture: flavor decomposition • , , • , , • Simulations show the measurement remains sensitive even with NLO considerations

  7. Daniel Jumper - DNP 2012 Polarized pp at RHIC • “Siberian Snakes” • Flip spin twice per rotation • Lessens depolarizing effects of accelerator • Randomized spin direction per bunch • Alternating spin patterns give more consistent relative luminosity • Polarized pp collisions at =200-500 GeV • Longitudinal or transverse

  8. Daniel Jumper - DNP 2012 Polarized pp at RHIC • “Siberian Snakes” • Flip spin twice per rotation • Lessens depolarizing effects of accelerator • Randomized spin direction per bunch • Alternating spin patterns give more consistent relative luminosity • Polarized pp collisions at =200-500 GeV • Longitudinal or transverse

  9. Daniel Jumper - DNP 2012 PHENIX Forward Muon Trigger Upgrade • Experimental Challenge: • Trigger dominated by background especially at low • Solution: • Upgraded trigger system: • Tracking detectors now included in trigger allowing discrimination • RPC detectors added • Precise timing rejects non-collision related background • Additional tracking point • New vertex tracker

  10. Daniel Jumper - DNP 2012 Signal Background and Simulations • Simulations developed for 2011 analysis • Accurate estimated background levels in simulation used for correction factor in real data

  11. Daniel Jumper - DNP 2012 Initial Results • 2011 Results • ~25 Luminosity • ~50% Polarization • 2012 Run: Analysis in progress • ~50 Luminosity • Largest portion of data will come from upcoming 2013 run 2011 run results

  12. Daniel Jumper - DNP 2012 Projected Results • Projection for 500 delivered luminosity • ~55% polarization

  13. Daniel Jumper - DNP 2012 Conclusion • W Asymmetry offers a cleaner and more direct probe of sea quark spin • PHENIX’s forward upgrade is ready for W measurment • An analysis framework is in place • 2013 statistics will make a significant contribution toward tighter constraints of , Courtesy of Daniel de Florian, Rodolfo Sassot, Marco Stratmann, and Werner Vogelsang

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