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Spin Physics with Muons

Spin Physics with Muons. Ming X. Liu Los Alamos National Lab Physics Motivations Highlight of Baseline Physics Run3 and Beyond New Development. RHIC-Spin Physics New Frontier of Nucleon Structure Research. Proton Spin - a major puzzle from polarized DIS experiments

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Spin Physics with Muons

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  1. Spin Physics with Muons Ming X. Liu Los Alamos National Lab Physics Motivations Highlight of Baseline Physics Run3 and Beyond New Development

  2. RHIC-Spin Physics New Frontier of Nucleon Structure Research • Proton Spin -a major puzzle from polarized DIS experiments • Proton Spin Decomposition • Origin of Proton Spin: • gluon, sea quarks, orbital angular momentum ? • DIS can’t directly probe gluonsand anti-quarks • Need a new tool : RHIC-SPIN • a polarized proton collider • quark-gluon, quark-quark and gluon-gluon interactions • directly explore gluon and sea quark distributions Experimentally

  3. The Experiment • Polarized Protons at RHIC • E_cm=50 - 500 GeV • Pol=70% • L=2x10^32 cm^-2sec^-1 • Particle Detectors • PHENIX et al • Physics Studies • Nucleon Spin Structure • Gluon distribution • Quark distribution • New Physics

  4. Experimental Observables • Asymmetries

  5. What do we learn from such measurements ? • Asymmetries • Polarized Quark and Gluon Distributions - LO • Proton Structure • QCD dynamics

  6. 1.5 2 5 Gluon Polarization and Heavy Quarks • Heavy Quark production at 200 GeV • Distinct Experimental signatures • high Pt lepton • 2nd vertex • Large asymmetry and pQCD ALL

  7. +  W+ - s lepton  W- Pt Jet b c VTX b _ b IP Heavy Quark and Quarkonium @PHENIX • Exp. Signatures • full reconstruction • D -> kπ • J/Psi -> μ+μ- • semi-leptonic decay • BR ~10% (c, b) • charge correlation • Long lifetimes* • 2nd VTX (Upgrade Plan) • A common device in Coll. Exp’s

  8. 30% Expectations from Y03: ΔG • 1st longitudinally polarized p-p collisions @200GeV • L=0.35 /pb; pol =30% ALL from muons PB=30%, 1k J/Psi Single Muon Pt J/Psi Pt

  9. Sea Quark Polarization & Flavor Asymmetry • Nucleon is a complex system • Sea quarks and gluons correlated • QCD dynamics LANL/E866

  10. Quark and Anti-Quark Polarization Bunce G. et al, hep-ph/0007218

  11. 1.5 2 5 SUSY SM: QQbar Physics Beyond the SM with Polarized Beams PRL 86, 4231(2001) Novel ideas for new physics search Spin Asymmetry - advantage over traditional unpolarized beams SUSY search Light glunio hypothesis

  12. + J/ * - Study J/ Production Mechanism- J/Psi polarization - a key probe?- Spin dynamics in pQCD α= +1: transversely polarized α= -1: longitudinally polarized α= 0: no polarization hep-ph/0106120 M. Kramer

  13. Asymmetries from J/Psi ALL Asymmetry J/Psi Polarization PRD 56 (1997)A. Tkabladze &O. Teryaev PRL 87 (2001) F.Yuan & K. Chao

  14. Summary • Muons from polarized p-p collisions • A unique tool to study: • polarized gluon and sea-quark distributions • pQCD/NRQCD factorization model • heavy quarkonia production mechanism • QGP probe? • a new tool for physics beyond the Standard Model • VTX + muon –> “B” physics • Expectations from Y03 p-p run • statistically limited for pol. measurements • open charm and beauty X-sections are possible • Very rich physics program in coming years (2005+) • Polarization • Spin asymmetry • Pol PDF

  15. ｂ→e ｂ→ Heavy Quark Production and G(x) • Gluon’s x range Central Arm ｂ→e proton ｂ→ x1P x2P Muon Arm Central Arm

  16. Muon Probe @PHENIX • Heavy quarks • Open Charm/Beauty • Quarkonium, DY • Light hadrons • Kaon, Pion • W,Z decays • Hard probes • pQCD and Factorization • LO/NLO • Spin : soft ? Hard? QCD CC BB Muon Pt

  17. “Muon” as a hadron tag - turn background into signal - • Low Pt pi/kaon decay • ~0.2% pi->mu • Punch through hadrons (pions) • ~0.6% pi->pi, tagged by MUID • Large statistics Pt Pt

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