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Highlights from PHENIX II: Photons and Leptons

This presentation discusses the production and rare processes of photons and leptons in PHENIX experiments, emphasizing the need for large data samples and precise background determination. It also highlights improved measurements in p+p and Au+Au collisions, nuclear suppression dependence on energy and particle species, direct photon measurements, and J/ψ production.

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Highlights from PHENIX II: Photons and Leptons

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  1. Highlights from PHENIX II:Photons and Leptons Terry Awes, ORNL For the PHENIX collaboration

  2. Photons and Leptons • Penetrating probes that carry information about their production. • Rare processes • Need large data samples • Large backgrounds • Need precise background determination • Background  from decays of  and  • Electrons from  conversions • Combinatorial Backgrounds • Theme: Towards Higher Accuracy Terry Awes, ORNL - QM08, Jaipur India

  3. More Precise Measurements  Au+Au 200 GeV (Run 4) • Improved Statistical errors • Au+Au Statistics: • 30 : 10 : 1 ( Runs 7 : 4 : 2 ) • Improved Systematic errors • More statistics • Two EMCals arXiv:0801.4020 Terry Awes, ORNL - QM08, Jaipur India

  4. Improved p+p Reference Data  p+p 62 GeV (Run 6) • PHENIX 62 GeV p+p  cross section approx. 2 times higher than ISR average. • 200 GeV p+p data 10x (with Run5) J.Phys.G31:S491 (2005) Terry Awes, ORNL - QM08, Jaipur India

  5. Nuclear Suppression Dependence on: Energy Particle Species  Cu+Cu 22,62,200 GeV (Run 5)  Au+Au 200 GeV (Run 4) g    arXiv:0801.4555 • Model calculations indicate quenching expected at sNN = 22 GeV, but Cronin effect dominates • Species dependence to probe space/time of suppression Terry Awes, ORNL - QM08, Jaipur India

  6. Dependence of Nuclear Suppression NPart Pathlength • RAA scales with Npart at same sNN • Some indication for “higher order” effects • Approximate scaling with <L> • Use RAA(Npart, sNN, Species, Pathlength) to illuminate models PHENIX PRC 76 034904 Session I: Klaus Reygers Terry Awes, ORNL - QM08, Jaipur India

  7. Direct Photons

  8. Towards inclusive  ( contribution)  Au+Au 200 GeV Poster: B.Sahlmuller • Universal  mT-scaling • Independent of centrality in Au+Au  p+p systematics PHENIX Preliminary PRC 75, 024909 (2007) PRC 75, 024909 (2007) Terry Awes, ORNL - QM08, Jaipur India

  9. PHENIX Preliminary • Run 4 (QM06): High pT suppression • Isospin (PDF) effect (+ ?) Direct  Au+Au: Direct = Inclusive-Decay • Run 2: No  suppression -> Jet quenching (PRL 94, 232301 (2005)). Terry Awes, ORNL - QM08, Jaipur India

  10. Direct  RAA Results Central Cu+Cu 200 GeV (Run 5) Direct  RAA vs Npart • Direct  RAA 1 • Is there other evidence for nuclear effects? • Reduced/enhanced radiation due to jet quenching PHENIX Preliminary Min Bias Au+Au 62 GeV (Run 4) PHENIX Preliminary Session VIII: Takao Sakaguchi Terry Awes, ORNL - QM08, Jaipur India

  11. Direct  v2 : Au+Au 200 GeV Direct  v2 Min Bias Au+Au 200 GeV (Run 4) • Interested in sign of direct  v2 (at high pT): • Positive == parton emission quenched • Negative == parton emission (Brems.) enhanced • Results suggest positive v2 Session XV: Kentaro Miki Terry Awes, ORNL - QM08, Jaipur India

  12. ~D(z) Poster: A.Hanks Use Near Side peak to determine direct  associated with h, I.e. fragmentation photons -h Correlations Session XV: Matthew Nguyen •  “measures” recoil parton momentum • Measure fragmentation function D(Z) -h p+p 200 GeV (Run 5) Terry Awes, ORNL - QM08, Jaipur India

  13. J/ Production

  14. J/ d+Au: Cold Nuclear Matter J/ RdAu 200 GeV • Increased Run 5 p+p statistics (x10 Run 3) • Improved & consistent p+p and dAu analysis • Improved alignment, resolution, yield extraction,… • Cancellation of systematic errors in RdAu • Result: CNM = Shadowing(EKS) + Breakup = 2.8 mb • Consistent within errors with previous results • and with Breakup=4.2+/-0.5mb (SPS result) +1.7 -1.4 arXiv:0711.3917 Session VI: Matthew Wysocki Terry Awes, ORNL - QM08, Jaipur India

  15. |y| < 0.35 J/ Au+Au: CNM Effects J/ RAuAu 200 GeV (Run4) • Large errors still (need Run 8 d+Au, Run 7 Au+Au) • Comparison suggests more forward suppression beyond CNM than at mid-rapidity • BUT models shown don’t describe RdAu impact parameter dependence 1.2 < |y| < 2.2 arXiv:0711.3917 Terry Awes, ORNL - QM08, Jaipur India

  16. J/ RAA Cu+Cu and Au+Au J/ RAA 200 GeV • Approx 2x more J/ in Cu+Cu sample than Au+Au sample • More precise Npart<100 info • Curves show RAA prediction from ad hoc CNM fit to RdAu separately at y=0 and y > 1.2 • CNM from RdAu fit describes suppression for Npart < 100. Session XVIII: Susumu Oda RdAu constraints are not sufficient to say if suppression beyond cold nuclear matter is stronger at forward rapidity arXiv:0801.0220 Terry Awes, ORNL - QM08, Jaipur India

  17. J/ <pT2> Cu+Cu and Au+Au • No (or modest) pT broadening of J/ • Conspiracy of low pT suppression and recombination? arXiv:0801.0220 Session XVIII: Susumu Oda Terry Awes, ORNL - QM08, Jaipur India

  18. Low Mass e+e-

  19. Electron Pair Mass Spectrum p+p Mee p+p 200 GeV (Run5) Unlike sign • Combinatorial Bkground subtraction error 0.25% • Confirmed with special convertor runs • Correlated unlike (and like) pairs due to jet and Dalitz photon pair conversions Like sign arXiv:0801.0220 Terry Awes, ORNL - QM08, Jaipur India

  20. Hadronic Cocktail to Calculate Mee • Based on PHENIX measurements • (Light VM See Session XXIII Y. Nakamiya) • Fit to pion spectrum provides excellent fit to all other mesons with MT-scaling assumption • MT-scaling works very well arXiv:0802.0050 Terry Awes, ORNL - QM08, Jaipur India

  21. Measured p+p Mee compared to Cocktail • Cocktail filtered in PHENIX acceptance • Charm, Bottom, DY contributions from PYTHIA • Excellent agreement! arXiv:0802.0050 Terry Awes, ORNL - QM08, Jaipur India

  22. c dominant b dominant Heavy Quarks in p+p from e+e- After subtraction of Cocktail - Fit to a*charm+ b*bottom (with PYTHIA shape) • Good agreement with single e results • Also new analyses via e-h coincidences, single muons, and direct charm measurement • See talks: Session XIV: Yuhei Morino Donny Hornback arXiv:0802.0050 Terry Awes, ORNL - QM08, Jaipur India

  23. Bottom Measurement p+p 200 GeV Charm and bottom extracted via e-h mass analysis • Charm and bottom spectra both x above FONLL calculations • But ratio is in good agreement with FONLL Session XIV: Yuhei Morino Terry Awes, ORNL - QM08, Jaipur India

  24. Preliminary Run 7 HF v2 result: Poster: A.Dion Heavy Flavor via non-photonic Electrons • HF strongly suppressed, Significant v2 • Implies high density, small diffusion coefficient • Estimate /s = (1.3-2)/4 • Very close to conjectured limit Session XIV: Ralf Averbeck PHENIX : PRL98, 172301 (2007) Terry Awes, ORNL - QM08, Jaipur India

  25. Thermal contribution perhaps if ccbar mass spectrum softened by rescatt. Au+Au Mee compared to Cocktail • Data and Cocktail absolutely normalized • Cocktail normalized to Au+Au measurements • Except ccbar • Low mass excess • 150 < Mee < 750 • X 3.4±0.2(stat.) ±1.3(syst.)±0.7(model) • Intermediate mass agreement arXiv:0706.3034 Terry Awes, ORNL - QM08, Jaipur India

  26. 0 < pT < 8 GeV/c 0 < pT < 0.7 GeV/c 0.7 < pT < 1.5 GeV/c 1.5 < pT < 8 GeV/c • Still significant at high pT PT Dependence of Au+Au Mee • Low Mass excess is a low pT enhancement • Huge excess at lowest pT • Late Phase info PHENIX Preliminary Session XI: Alberica Toia Terry Awes, ORNL - QM08, Jaipur India

  27. High pT Direct  Yield from * • Virtual with pT >> mee should be produced directly with a rate and mass distrib. that follows a “Dalitz” form fdir with MHad->oo • Extract Direct * “excess” as fraction r of fdir needed to describe low mass excess • That direct * fraction of inclusive * (mostly and ) should be the same as the real  fraction of inclusive  (mostly and ) Terry Awes, ORNL - QM08, Jaipur India

  28. Direct  via  * for p+p, Au+Au • New p+p result with * method agrees with NLO pQCD predictions, and with statistical method at high pT • Confirmation of the method • For Au+Au (QM05 result) there is a significant low pT excess above p+p expectations • Interpreted as thermal emission -> Initial T Session XV: Torsten Dahms arXiv:0801.xxxx Terry Awes, ORNL - QM08, Jaipur India

  29. -h correlations • Heavy Flavor • J/ |y| < 0.35 • Initial T and evolution • Low pT direct  excess • Dilepton excess Summary • More precise studies of sQGP matter • Systematics of RAA Terry Awes, ORNL - QM08, Jaipur India

  30. PHENIX Data Sets Terry Awes, ORNL - QM08, Jaipur India

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