Muon Production in Forward and Backward Rapidities in
Muon Production in Forward and Backward Rapidities in d. Au 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 M. X. Liu QM 04
Motivation • Nuclear medium effects in forward and backward directions in d. Au reactions – Different “x” range: initial state • (anti)shadowing/CGC C. M. F. – Final state (co-moving): very much energy dependent • Flavor dependence? θ ~10 Ge. V – Heavy flavors • Open charm, beauty – Light hadrons Au rest frame ~1000 Ge. V M. X. Liu QM 04
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 QM 04
Questions 1. What happens in the forward (d) AND backward (Au) directions? 2. Any collision centrality dependence? 3. Charge dependence? • h+ vs h- 4. Flavor dependence? • Light vs heavy quarks M. X. Liu QM 04
PHENIX Muon Detectors • Muon arms – – 1. 2<|η|<2. 4 Δφ=2π P>2 Ge. V/c Triggers • “Muons” – Stopped hadrons – Light meson decays – Heavy decays d Au M. X. Liu QM 04
Measurement of Stopped Hadrons Muon peak Stopping power: Use shallow Mu. ID absorber layers to select stopped Hadronic tail hadrons for Ptot > 1. 9 Ge. V: muon contamination < 3% M. X. Liu QM 04
Muon Production • Origins of muons – PYTHIA p+p @ √s=200 Ge. V – low PT: • light hadron decays – high PT: • Heavy quark decays Muon PT distribution M. X. Liu QM 04
Muons from Light Meson Decays • Muon event collision vertex distribution m Muon detector p absorber Collisions Vertex Z M. X. Liu QM 04
Measurements of Light/Heavy • Muons from light meson decays 1. 5 < PT < 2. 0 • Prompt muon PT distributions 1. Light hadron punchthroughs(work in progress) 2. Charm/Beauty! PT M. X. Liu QM 04
Centrality Dependence of Particle Production @Fwd/Bwd Directions 1. Stopped hadrons – Mesons + Baryons 2. Light mesons – Pions + Kaons 3. Heavy flavors – Charm + Beauty d Au M. X. Liu QM 04
Phenix Preliminary Au d Stopped Hadrons! M. X. Liu QM 04
Phenix Preliminary Au d Stopped Hadrons! M. X. Liu QM 04
Phenix Preliminary d Cronin effect & anti-shadowing? Stopped Hadrons! M. X. Liu QM 04 Au
RCP(y): Muons from Light Meson Decays Phenix Preliminary RCP M. X. Liu QM 04
RCP(y): Charge Dependence Phenix Preliminary + μ μ M. X. Liu QM 04
Answers to Previous Questions 1. What happens in the forward (d) AND backward (Au) direction? ☺ 2. Centrality dependence? ☺ 3. Charge dependence? ☺ • h+ vs h- 4. Flavor dependence? • Light vs heavy quarks M. X. Liu QM 04
Amazing Grace “I once was lost but now I am found” η=0 Au+Au at 200 Ge. V (2003 BNL d. Au PR) η=2 BRAHMS preliminary BRAHMS M. X. Liu QM 04 preliminary
Summary and Outlook • RCP @ forward and backward rapidity – Very different from y = 0 ! • Forward : suppression! • Backward: enhancement! – Parton scattering/energy loss – Parton (anti)shadowing Au • Work in progress d – Open heavy flavors – RCP with heavy flavors Posters – <Q 13>Anuj Purwar/Chun Zhang, “Charged hadron RCP measurement using the Phenix Muon Arms for d-Au collisions at 200 Ge. V ” – <Q 27>Dave Lee, “Muon production in forward and backward rapidity in d. Au collisions” – <Q 3> Ken Read; <Q 5> Youngil Kwon; <Q 6> Andy Glenn. M. X. Liu QM 04
Backup Slides M. X. Liu QM 04
Probed “x” region of Au Fermi Effect enhancement Blue band: d direction Saturation? Shadowing/suppression regime shadowing Yellow band: Au direction Anti-shadowing/Cronin regime M. X. Liu QM 04 EMC effect
Phenix Preliminary RCP(PT): muons from light meson decays M. X. Liu QM 04
RCP from J/Psi • Forward vs Backward R. G. de Cassagnac Friday/Parallel 3 M. X. Liu QM 04
More on nuclear medium effects Rd. Au(PT , y, …) • Energy dependent nuclear cross section • Gluon shadowing model backward forward Kopeliovich et al hep-ph/0104256 & hep-ph/0205151 M. X. Liu QM 04
Check the selected hadron sample using event vertex Tracks stop at gap 2 or gap 3 and 3 sigma muon exclusive M. X. Liu QM 04
Muon Event Vertex Distribution 1. Min. Bias event vertex 2. Muon event vertex 3. Normalized vertex 1 d 3 = “ 2” / ” 1” Au M. X. Liu Z-vtx QM 04 2
Central Arms y =0 M. X. Liu QM 04
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