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Recent Results from . . on Heavy Flavor and Electromagnetic Probes at RHIC

Recent Results from . . on Heavy Flavor and Electromagnetic Probes at RHIC. Andrew Glenn University of Colorado for the PHENIX collaboration March 27, 2006. Outline. Electromagnetic Probes Direct Photons Virtual Photons Heavy Flavor Production Open Charm Hidden Charm (J/ Ψ ).

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Recent Results from . . on Heavy Flavor and Electromagnetic Probes at RHIC

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  1. Recent Results from .. on Heavy Flavor and Electromagnetic Probes at RHIC Andrew Glenn University of Colorado for the PHENIX collaboration March 27, 2006

  2. Outline • Electromagnetic Probes • Direct Photons • Virtual Photons • Heavy Flavor Production • Open Charm • Hidden Charm (J/Ψ) Andrew Glenn

  3. Electromagnetic Probes Freeze-out Hadronization Hard Scattering Au Au  time γ e-  e+  Expansion  QGP Thermaliztion space • electro-magnetic radiation: g, e+e-, m+m- • rare, emitted “any time”; reach detector unperturbed by strong final state interaction Andrew Glenn

  4. Photon Sources • Initial hard scattering(p+p) pQCD • Thermal radiation from QGP (1<pT<3GeV) • Hadron-gas interaction (pT<1GeV/c)()  (), K*  K • Compton scattering in hard scattered and thermal partons (Jet-photon conversion) • Bremsstrahlung of hard scattered partons in medium (small compared to the above) PRC 69(2004)014903 Andrew Glenn

  5. Direct Photon Baseline Nuclear Modification factor S.S.Adler, et. al. (PHENIX Collaboration), PRL 94, 232301(2005) NO direct photon suppression (initial state), and large 0 suppression (final state) Andrew Glenn

  6. Including Virtual Photons phase space factor 1 for high pT g • Ratios of Minv bins to lowest one • If no direct photons: ratios can be calculated from Dalitz decays • If excess: direct photons Ratios Andrew Glenn

  7. Thermal Hint? p+p direct photon • For pT<3GeV/c, thermal photon contribution looks dominant • However, recent p+p result needs to be considered • Factor of ~4 larger than NLO pQCD at 3GeV/c! (still within error, though) • Smaller errors on real photon will help for making a conclusion. pQCD is LO! NLO pQCD: L.E.Gordon and W. Vogelsang, PRD48(1993)3136 Andrew Glenn

  8. High Mass Virtual Photons Dilepton continuum Andrew Glenn Measurement of Low Mass Dielectron Continuum in sqrt(s_NN)=200GeV Au-Au Collisions in the PHENIX Experiment at RHIC Alberica Toia Stony Brook University

  9. Photon Highlights • High pT (>6GeV/c ) photon yield is well described by NLO pQCD calculation • Virtual photon measurement using very low mass dileptons improves error bars at low pT • Hint of non-pQCD (thermal?) photons in central collisions Andrew Glenn

  10. Heavy Quarks • Carry the information of early stage of collisions. • Charm quark is massive (even at RHIC energy). • Creation takes place only at the beginning of collisions. • How are heavy quarks are effected by the medium? Andrew Glenn

  11. Heavy flavor electrons in p+p Andrew Glenn

  12. Prompt  in p+p PHENIX Preliminary Appears to be little rapidity dependence of heavy quark production in p+p (large errors though) Andrew Glenn Measurement of Open Heavy Flavor with Single Muons in pp and dAu collisions at 200 GeV Xiaorong Wang, New Mexico State University

  13. Quark Energy Loss   • What about heavy quarks ? • 2001, proposed “dead cone” effect suggests smaller energy loss of charm • Recent theories propose energy loss of charm quark is similar to light quarks. • (Armesto et al, PRD 71, 054027, 2005; M. Djordjevic et al., PRL 94, 112301, 2005.) Andrew Glenn

  14. Heavy Flavor in Au+Au preparing the high pT spectrum (up to pT = 10 GeV/c). Andrew Glenn

  15. Heavy Flavor RAA in Au+Au (1) q_hat = 0 GeV2/fm (4) dNg / dy = 1000 (2) q_hat = 4 GeV2/fm (3) q_hat = 14 GeV2/fm Theory curves (1-3) from N. Armesto, et al., PRD 71, 054027 (4) from M. Djordjevic, M. Gyullasy, S.Wicks, PRL 94, 112301 • We see strong suppression even for heavy quark (charm). • The data provides a strong constraint on the energy loss models. Andrew Glenn Medium Modification of Heavy Flavor Production Measured by PHENIX in Au+Au Collisions at sqrt(s_NN)=200 GeV Alan Dion State University of New York at Stony Brook

  16. Open Charm Flow in Au+Au Theory:Greco, Ko, Rapp: PLB 595 (2004) 202 • Significant anisotropy is observed for heavy flavor electron. • v2 has good agreement of charm flow assumption below pT < 2.0 GeV/c • In high pT region (pT > 2 GeV/c), v2 is reduced. (b quark contribution?) Andrew Glenn The Azimuthal Anisotropy of Electrons from Heavy Flavor Decays in sqrt{s_{NN}}=200 GeV Au-Au Collisions at PHENIXShingo Sakai University of Tsukuba Elliptic flow of inclusive single muon in sqrt(s_NN) = 200 GeV Au+Au collision at PHENIX IhnJea Choi Yonsei University

  17. Theory Aside In a calculation by Teaney and Moore (hep-ph/0412346), they calculate the expected elliptic flow (v2) and transverse momentum modifications for different charm quark diffusion coefficients. The two effects go hand in hand. Anything that increases the cross section for interactions will have this general effect. Andrew Glenn

  18. Open Charm Highlights • Binary scaling of total charm yield works well. • Nuclear modification factor RAA shows a strong suppression at high pT region. • Non zero v2 of heavy flavor electron observed. • HEAVY QUARKS ARE SIGNIFICANTLY AFFECTED BY THE MEDIUM Andrew Glenn

  19. J/ Production • Formation of J/Y • by cc coalescence • Comover scattering Mixed phase Freeze out QGP Nuclear • Gluon Shadowing • (Modification of • PDF in nuclei) • Color screening • (Dissociation by gluons) • Nuclear absorption • by the spectators • Cronin effect Need to understand the J/Y production in each collision stage. Andrew Glenn

  20. RAA of J/ in Au+Au/Cu+Cu 1.2<|y|<2.4 |y|<0.35 Constrained by d+Au • Suppression increased toward the central collisions.Factor of 3 suppression at most central (Au+Au) • Beyond the suppression from cold matter effect. • Same pattern between Au+Au and Cu+Cu at forward-rapidity, but different pattern at mid-rapidity. Andrew Glenn

  21. RAA and Suppression Models J/Y suppression at RHIC is over-predicted by the suppression models that described SPS data successfully. Co-mover (sabs = 1mb) Direct dissociation (+Comover) QGP screening (+Comover, feed down) Andrew Glenn

  22. Recombination Models • Better matching with results compared to the suppression models. • Don’t forget about free paramerters. • At RHIC (energy): Recombination compensates stronger suppression? Andrew Glenn

  23. Invariant pT distributions Cu+Cu Extraction of <pT2> by fittingwith A(1+(pT/B)2)-6 Andrew Glenn

  24. <pT2> as a function of Ncol Au+Au = RED Cu+Cu = BLUE Dashed: without recombination Solid: includes recombination Recombination model matches better to the data... But don’t forget the error bars nucl-th/0505055 Andrew Glenn

  25. Connected Observables Npart Suppression due to multiple scattering in cold nuclear matter A.M. Glenn, Denes Molnar, J.L. Nagle nucl-th/0602068 Andrew Glenn

  26. Rapidity dependence Cu+Cu (200GeV) 0-20% PHENIX Preliminary PHENIX Preliminary 0-20% 20-40% AuAu 20-40% 40-93% 40-60% 60-94% p+p p+p CuCu nucl-th/0507027 nucl-th/0505055 • No significant change in rapidity shape in Au+Au and Cu+Cu. • RAA is flat (within errors) as a function of rapidity, which is not predicted by the recombination model. Andrew Glenn

  27. RAA vs. pT in Au+Au/Cu+Cu • Suppression of J/Y yield at low pT in both Au+Au and Cu+Cu. • High pT J/Y escape the medium? Leakage effect? [Phys. Lett. B 607 (2005)] • Might one expect “pile up” at low pT for recombination+energy loss? Andrew Glenn

  28. J/Y Highlights • Factor of 3 (4 Cu+Cu) suppression in most central collisions • Beyond the suppression from cold matter effects. • Over-predicted by the suppression models effective for SPS. • Possible signs of recombination, but plenty of open questions (flies in the ointment?) Andrew Glenn J/Psi measurements in Cu+Cu and Au+Au collisions at sqrt(s) = 200 GeV by PHENIX at RHICAndry RakotozafindrabeLaboratoire Leprince Ringuet (LLR) - École Polytechnique (France)

  29. Brazil University of São Paulo, São Paulo China Academia Sinica, Taipei, Taiwan China Institute of Atomic Energy, Beijing Peking University, Beijing France LPC, University de Clermont-Ferrand, Clermont-Ferrand Dapnia, CEA Saclay, Gif-sur-Yvette IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, Orsay LLR, Ecòle Polytechnique, CNRS-IN2P3, Palaiseau SUBATECH, Ecòle des Mines at Nantes, Nantes Germany University of Münster, Münster Hungary Central Research Institute for Physics (KFKI), Budapest Debrecen University, Debrecen Eötvös Loránd University (ELTE), Budapest India Banaras Hindu University, Banaras Bhabha Atomic Research Centre, Bombay Israel Weizmann Institute, Rehovot Japan Center for Nuclear Study, University of Tokyo, Tokyo Hiroshima University, Higashi-Hiroshima KEK, Institute for High Energy Physics, Tsukuba Kyoto University, Kyoto Nagasaki Institute of Applied Science, Nagasaki RIKEN, Institute for Physical and Chemical Research, Wako RIKEN-BNL Research Center, Upton, NY Rikkyo University, Tokyo, Japan Tokyo Institute of Technology, Tokyo University of Tsukuba, Tsukuba Waseda University, Tokyo S. Korea Cyclotron Application Laboratory, KAERI, Seoul Kangnung National University, Kangnung Korea University, Seoul Myong Ji University, Yongin City System Electronics Laboratory, Seoul Nat. University, Seoul Yonsei University, Seoul Russia Institute of High Energy Physics, Protovino Joint Institute for Nuclear Research, Dubna Kurchatov Institute, Moscow PNPI, St. Petersburg Nuclear Physics Institute, St. Petersburg St. Petersburg State Technical University, St. Petersburg Sweden Lund University, Lund 12 Countries; 58 Institutions; 480 Participants* USA Abilene Christian University, Abilene, TX Brookhaven National Laboratory, Upton, NY University of California - Riverside, Riverside, CA University of Colorado, Boulder, CO Columbia University, Nevis Laboratories, Irvington, NY Florida State University, Tallahassee, FL Florida Technical University, Melbourne, FL Georgia State University, Atlanta, GA University of Illinois Urbana Champaign, Urbana-Champaign, IL Iowa State University and Ames Laboratory, Ames, IA Los Alamos National Laboratory, Los Alamos, NM Lawrence Livermore National Laboratory, Livermore, CA University of New Mexico, Albuquerque, NM New Mexico State University, Las Cruces, NM Dept. of Chemistry, Stony Brook Univ., Stony Brook, NY Dept. Phys. and Astronomy, Stony Brook Univ., Stony Brook, NY Oak Ridge National Laboratory, Oak Ridge, TN University of Tennessee, Knoxville, TN Vanderbilt University, Nashville, TN *as of January 2004 Andrew Glenn

  30. BONUS SLIDES Andrew Glenn

  31. Related talks at SQM • Elliptic flow of inclusive single muon in sqrt(s_NN) = 200 GeV Au+Au collision at PHENIXIhnJea Choi Yonsei University • Medium Modification of Heavy Flavor Production Measured by PHENIX in Au+Au Collisions at sqrt(s_NN)=200 GeVAlan Dion State University of New York at Stony Brook • J/Psi measurements in Cu+Cu and Au+Au collisions at sqrt(s) = 200 GeV by PHENIX at RHICAndry RakotozafindrabeLaboratoire Leprince Ringuet (LLR) - École Polytechnique (France) • The Azimuthal Anisotropy of Electrons from Heavy Flavor Decays in sqrt{s_{NN}}=200 GeV Au-Au Collisions at PHENIXShingo Sakai University of Tsukuba • Measurement of Low Mass Dielectron Continuum in sqrt(s_NN)=200GeV Au-Au Collisions in the PHENIX Experiment at RHICAlberica Toia Stony Brook UniversityMeasurement of Open • Heavy Flavor with Single Muons in pp and dAu collisions at 200 GeVXiaorong Wang, New Mexico State University Andrew Glenn

  32. PHENIX experiment Centrality measurement: Beam Beam Counters together with Zero degree calorimeters Centrality is mapped to Npart (Ncol) using Glauber model Central Arms: Hadrons, photons, electrons J/y  e+e- |h|<0.35 Pe > 0.2 GeV/c Df = p (2 arms x p/2) • Muon Arms: • Muons at forward rapidity • J/y  m+m- • 1.2< |h| < 2.4 • Pm > 2 GeV/c • Df = 2p Andrew Glenn

  33. Including Virtual Photons 0-30 90-140 200-300 140-200 Rdata ÷ ÷ e+ Compton e- g* ÷ q g q • Measure inclusive electron pairs or photons • Measure 0 and  spectra via 2 decay, and estimate background electron-pairs or photon distribution • Other hadron spectra estimated by mT scaling of power-law fit to 0 • Conservative assumption on normalization:/0=0.450.05, /0=1.0, ’/0=1.0 • Look for an excess of signals over background Very low-mass dileptons Kroll-Wada Formula phase space factor is unity for high pTg • Ratios of Minv bins to lowest one (Rdata) • If no direct photons: the ratios become exactly what can be calculated from Dalitz decay formula above • If excess over calculation: direct photons Andrew Glenn

  34. Results and very low-mass dilepton (~21% relative error to ratio) •  excess ratio (measured/background) • Systematic error revisited and improved: pT-correlated: 7.5%, point-by-point: 7.0% • Consistent with Run2 Note that *dir / *incl +1 is slightly different from meas / background. Centrality range is different as well. Mass Range:0<Mee<30MeV/c2 (calculated from that in 90<Mee<300MeV/c2) Andrew Glenn

  35. Very low mass dilepton ratio converted to direct photon spectrum Assumption: dir / incl = *dir / *incl (for Mee << M) dir = *dir / *incl  incl incl is real inclusive photon A Thermal Hint? Additional ~10 % systematic error from inclusive included Overlaid with thermal + pQCD calc. D. d’Enterria, D. Perresounko, nucl-th/0503054 Andrew Glenn

  36. Direct photon in higher mass Dilepton? Contribution of direct photons converted into electron pairs? Try to see what it looks like Take the direct photon spectra Kroll-Wada’s formula to convert direct photon to electron-pair spectra Phase space factor considered (1-mee2/M2)3 M = E, |F(mee)| = 1 Acceptance filter for PHENIX is not applied Look at higher mass region. 0 0-20% centrality pT>1.0GeV/c  Direct photon internal conversion Probably not significant compared to predicted thermally radiating dilepton. Needs a detailed look with taking the acceptance into account. Andrew Glenn

  37. Cocktail comparison • Data and cocktail absolutely normalized • Cocktail from hadronic sources • Charm from PYTHIA • Predictions are filtered in PHENIX acceptance • Good agreement in p0 Dalitz • Continuum:hint for enhancement not significant within systematics • What happens to charm? • Single e  pt suppression • angular correlation??? • LARGE SYSTEMATICS! Andrew Glenn

  38. Data/cocktail Andrew Glenn

  39. Comparison with theory • calculations for min bias • QGP thermal radiation included • Systematic error too large to distinguish predictions • Mainly due to S/B • Need to improve •  HBD R.Rapp, Phys.Lett. B 473 (2000) R.Rapp, Phys.Rev.C 63 (2001) R.Rapp, nucl/th/0204003 Andrew Glenn

  40. Total Charm Yield in Run2 Au+Au S.S. Adler, et al., PRL 94 082301 • Binary scaling works well for total charm yield • dNe/dy is fit to ANcoll = 0.938+/-0.075+/-0.0018 • Coming soon: High statistic data in Run4 Au+Au Andrew Glenn

  41. Prompt  in Run3 d+Au d • Suppression(?) in d going direction • Enhancement(?) in Au going direction Au South North Beam direction Andrew Glenn

  42. Heavy flavor in Run3 d+Au Minimum Biasnon-photonic electrons PHENIX preliminary Andrew Glenn

  43. RAA of heavy flavor electrons (1a) q_hat = 0 GeV2/fm (2a) dNg / dy = 1000 (2b) dNg / dy = 3500 (1b) q_hat = 4 GeV2/fm (1c) q_hat = 14 GeV2/fm PRL accepted recently (nucl-ex/0510047). Clear evidence for strong medium effects! Theory curves (1abc) from N. Armesto, et al., PRD 71, 054027 (2ab) from M. Djordjevic, M. Gyullasy, S.Wicks, PRL 94, 112301 Andrew Glenn

  44. J/Y measurement • PHENIX measured the J/y yield in p+p, d+Au, Au+Au and Cu+Cu to understand the J/y production in each stage of collisions. • Base line for all measurements • sJ/y as a function ofrapidity, pT p+p collisions • Initial stage effect • Gluon shadowing • Nuclear medium effect • Nuclear absorption • Cronin effect • sJ/y as a function of • rapidity, pT, XAu d+Au collisions Andrew Glenn

  45. J/Y measurement • PHENIX measured the J/y yield in p+p, d+Au, Au+Au and Cu+Cu to understand the J/y production in each stage of collisions. • Extract the medium effect • Color screening • Coalescence • sJ/y (yield) as a function • rapidity, pT • collision centrality • collision species (Au+Au/Cu+Cu) • collision energy (200GeV/62.4GeV) p+p/d+Au collisions Au+Au collisions Cu+Cu collisions Note that feed down effect from cc and y’ is also important. But they are not accessible with the current RHIC luminosity. Andrew Glenn

  46. J/Y cross section in p+p p-p J/Psi – PHENIX 200GeV y nucl-ex/ 0507032 Accepted in PRL • Cross section vs. rapidity and energy dependence Integrated cross section s=2.61+-0.20(fit)+-0.26(abs)mb Gives a good base line for d+Au, Au+Au and Cu+Cu. Andrew Glenn

  47. J/Y in d+Au Collisions Xd XAu J/ in South y < 0 rapidity y Anti Shadowing Shadowing Xd XAu J/ in North y > 0 • Understand the cold matter effects • Gluon Shadowing • Cronin effect (pT broadening) • Nuclear Absorption • Coverage of XAu in d+Au at PHENIX South muon arm (y < -1.2) : • large XAu0.090 Central arm (y0) : • intermediate XAu  0.020 North muon arm (y > 1.2) : • small XAu  0.003 gluons in Pb / gluons in p X Eskola, et al., Nucl. Phys. A696 (2001) 729-746. Andrew Glenn

  48. J/Y in d+Au vs. pT nucl-ex/0507032 accepted in PRL • Cronin effect (pT broadening) • Observation of pT broadening at RHIC. • Initial state multiple scattering of partons Andrew Glenn

  49. pT broadening xAu~ 0.1 xAu~ 0.01 xAu~ 0.003 nucl-ex/0507032 Accepted in PRL sdAu = spp(2x197)a • Suppression factor a: • a vs. pT • Comparison to E866 at s = 39 GeV. Trend of pT broadening at RHIC is consistent with E866 results. Andrew Glenn

  50. Nuclear Absorption and Shadowing E866: PRL 84, 3256 (2000)NA3: ZP C20, 101 (1983) (in gold) nucl-ex/0507032 Accepted in PRL RdAu • RdAu vs. rapidity, centrality, a vs. x coverage 1.2 1.0 0.8 0.6 RdA 0.4 0.2 Rapidity 0 Weak nuclear absorption : s =1–3 mb (4.3 mb at SPS) Suppression increased weakly toward the central collisions. Weak shadowing (violation of XAu scaling) : a > 0.92 Andrew Glenn

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