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Muon Production in Forward and Backward Rapidities in dAu Collisions at RHIC

Muon Production in Forward and Backward Rapidities in dAu Collisions at RHIC. Ming X. Liu Los Alamos National Lab (for the PHENIX Collaboration) Key words heavy quark semileptonic decay light hadron weak decay (anti)shadowing/CGC. θ. Motivation.

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Muon Production in Forward and Backward Rapidities in dAu Collisions at RHIC

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  1. Muon Production in Forward and Backward Rapidities in dAu Collisions at RHIC Ming X. Liu Los Alamos National Lab (for the PHENIX Collaboration) Key words heavy quark semileptonic decay light hadron weak decay (anti)shadowing/CGC

  2. θ Motivation • Nuclear medium effects in forward and backward directions in dAu reactions • Different “x” range: initial state • (anti)shadowing/CGC • Final state (co-moving): very much energy dependent • Flavor dependence? • Heavy flavors • Open charm, beauty • Light hadrons C.M.F. ~10 GeV Au rest frame dAu: a test ground! ~1000 GeV M.X. Liu QM04

  3. Theoretical Predictions I. Vitev nucl-th/0302002 D. Kharzeev hep-ph/0307037 y=0 Gluon Shadowing/Saturation Increasing y y=+3 y=-3 M.X. Liu QM04

  4. Questions • What happens in the forward (d) AND backward (Au) directions? • Any collision centrality dependence? • Charge dependence? • h+ vs h- • Flavor dependence? • Light vs heavy quarks Is there shdowing/CGC at RHIC? M.X. Liu QM04

  5. d Au PHENIX Muon Detectors • Muon arms • 1.2<|η|<2.4 • Δφ=2π • P>2GeV/c • Triggers • “Muons” • Stopped hadrons • Light meson decays • Heavy decays M.X. Liu QM04

  6. Muon peak Hadronic tail Measurement of Stopped Hadrons Stopping power: Use shallow MuID absorber layers to select stopped hadrons for Ptot > 1.9GeV: muon contamination < 3% M.X. Liu QM04

  7. Muon Production • Origins of muons • PYTHIA p+p @ √s=200GeV • low PT: • light hadron decays • high PT: • Heavy quark decays Muon PT distribution M.X. Liu QM04

  8. Muon detector m p absorber Muons from Light Meson Decays • Muon event collision vertex distribution Collisions Vertex Z M.X. Liu QM04

  9. 1.5 < PT < 2.0 Measurements of Light/Heavy • Muons from light meson decays • Prompt muon PT distributions • Light hadron punch-throughs(work in progress) • Charm/Beauty! PT M.X. Liu QM04

  10. d Au Centrality Dependence of Particle Production @Fwd/Bwd Directions • Stopped hadrons • Mesons + Baryons • Light mesons • Pions + Kaons • Heavy flavors • Charm + Beauty M.X. Liu QM04

  11. PhenixPreliminary Au d Stopped Hadrons! M.X. Liu QM04

  12. PhenixPreliminary Au d Stopped Hadrons! M.X. Liu QM04

  13. PhenixPreliminary Cronin effect & anti-shadowing? d Shadowing? Au Stopped Hadrons! M.X. Liu QM04

  14. RCP(y): Muons from Light Meson Decays PhenixPreliminary RCP M.X. Liu QM04

  15. RCP(y): Charge Dependence PhenixPreliminary μ+ μ- M.X. Liu QM04

  16. Answers to Previous Questions • What happens in the forward (d) AND backward (Au) direction? ☺ • Centrality dependence? ☺ • Charge dependence? ☺ • h+ vs h- • Flavor dependence? • Light vs heavy quarks M.X. Liu QM04

  17. BRAHMS preliminary BRAHMS preliminary Amazing Grace “I once was lost but now I am found” η=0 η=2 Au+Au at 200GeV (2003 BNL dAu PR) M.X. Liu QM04

  18. Au d Summary and Outlook • RCP @ forward and backward rapidity • Very different from y= 0 ! • Forward : suppression! • Backward: enhancement! • Parton scattering/energy loss • Parton (anti)shadowing • Work in progress • Open heavy flavors • RCP with heavy flavors Posters • <Q13>Anuj Purwar/Chun Zhang, “Charged hadron RCPmeasurement using the Phenix Muon Arms for d-Au collisions at 200 GeV ” • <Q27>Dave Lee, “Muon production in forward and backward rapidity in dAu collisions” • <Q3> Ken Read; <Q5> Youngil Kwon; <Q6> Andy Glenn. Is there shdowing/CGC at RHIC? M.X. Liu QM04

  19. Backup Slides M.X. Liu QM04

  20. Fermi Effect enhancement Saturation? EMC effect shadowing Probed “x” region of Au Blue band: d direction Shadowing/suppression regime Yellow band: Au direction Anti-shadowing/Cronin regime M.X. Liu QM04

  21. RCP(PT): muons from light meson decays PhenixPreliminary M.X. Liu QM04

  22. RCP from J/Psi • Forward vs Backward R.G. de Cassagnac Friday/Parallel 3 M.X. Liu QM04

  23. Energy dependent nuclear cross section Gluon shadowing model More on nuclear medium effects RdAu(PT , y,…) backward forward Kopeliovich et al hep-ph/0104256 & hep-ph/0205151 M.X. Liu QM04

  24. Check the selected hadron sample using event vertex Tracks stop at gap2 or gap3 and 3 sigma muon exclusive M.X. Liu QM04

  25. d Au Muon Event Vertex Distribution • MinBias event vertex • Muon event vertex • Normalized vertex 1 2 3 = “2” / ”1” M.X. Liu QM04 Z-vtx

  26. Central Arms y =0 M.X. Liu QM04

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