J/  measurements at RHIC/PHENIX David Silvermyr, ORNL for the PHENIX collaboration

2 Outline Brief High-Energy Heavy-Ion physics and PHENIX Experiment intro Selected results; Charmonium : –J/  in dAu collisions; Shadowing, nuclear effects Summary and Outlook See also talks tomorrow by J. Velkovska, W. Vogelsang, about physics at RHIC. Poster by D. Hornback (UT) : open charm physics

3 Create very high temperature and density matter as existed ~10  sec after the Big Bang inter-hadron distances comparable to that in neutron stars collide heavy ions to achieve maximum volume Study the hot, dense medium is thermal equilibrium reached? transport properties? equation of state? do the nuclei dissolve into a quark gluon plasma? Collide Au + Au ions at high energy  s = 200 GeV/nucleon pair, p+p and d+A [Also polarized p+p collisions to study carriers of p’s spin] The Physics of RHIC

4 ’’Onia’’ production –Leading order at low x = ’’gluon fusion’’ Sensitive to: Final state Parton energy loss in the hot & dense medium ? Thermal enhancement ? Flow ? Initial state Parton distribution functions p T broadening Parton energy loss in the initial state ? Polarization ? J /  or  + feed-down (e.g. B or  c -> J/  ) Heavy Flavor Production

5 Pb-Pb collisions show suppression in excess of "normal" nuclear suppression J/ normalized to Drell-Yan vs “Centrality” Suppression Expectation NA50, Phys. Lett. B477 (2000) 28. Observation at CERN (NA50) * The J/  finds itself enveloped by the QGP(?) medium and dissolves. * The rarity of charm quarks makes it unlikely that they find each other at the hadronization stage Matsui/Satz Suppression Mechanism

6 We expect a screening of the attractive potential as we approach the deconfinement transition. This color screening may results in a decrease in the number of heavy quarkonia states. Alternative models predict enhancement from c-c coalescence as the collision volume cools.  Comparisons between various collision species are very important! RHIC has already had p-p, d-Au, and Au-Au runs.  Studies done via both dielectron and dimuon channels in PHENIX. Charmonia at RHIC

7 PHENIX Two central arms for measuring hadrons, photons and electrons Two forward arms for measuring muons Event characterization detectors in middle electrons: central arms electron measurement in range: |  |  0.35 p  0.2 GeV/c muons: forward arms muon measurement in range: 1.2 < |  | < 2.4 p  2 GeV/c

8 Year Ions  s NN LuminosityDetectorsJ/  2000 [Run-1] Au-Au130 GeV1  b -1 Central (electrons) Au-Au200 GeV24  b -1 Central [1] 2002 [Run-2] p-p200 GeV0.15 pb muon arm [2] 2002 d-Au200 GeV2.74 nb -1 Central [Run-3] p-p200 GeV0.35 pb muon arms [Run-4] Au-Au 200 GeV 62 GeV ~240 ub -1 ~9 ub -1 Central + 2 muon arms ? [thousands] ? [1] nucl-ex/ , Phys. Rev. C 69, (2004).nucl-ex/ Phys. Rev. C 69, (2004) [2] hep-ex/ , Phys. Rev. Lett. 92, (2004)hep-ex/ Phys. Rev. Lett. 92, (2004) RHIC History N J/  ~= 10 Run

9 At RHIC, J/  mostly produced by gluon fusion, and thus sensitive to gluon pdf Three rapidity ranges probe different momentum fractions of Au partons –South (y < -1.2) : large X 2 (in gold) ~ 0.09 –Central (y ~ 0) : intermediate X 2 ~ 0.02 –North (y > 1.2) : small X 2 (in gold) ~ X1X1 X2X2 J/  in North y > 0 X1X1 X2X2 J/  in South y < 0 rapidity y From Eskola, Kolhinen, Vogt Nucl. Phys. A696 (2001) Example of predicted gluon shadowing in d+Au gluons in Pb / gluons in p X Anti Shadowing J/    +  -/e+e- for dAu & pp North Muon ArmSouth Muon Arm d Au Central Arm

J/ψ’s  ~ 100 MeV J/ψ  e + e - |y|<0.35 J/ψ   +  - 1.2<|y|<2.4 +-+- ±±±± 780 J/ψ’s  ~ 165 MeV North Arm dAu J/    +  -/e+e- for dAu

11 In RUN3, we accumulated ~300nb -1 p-p and ~3nb -1 d-Au collisions. J/  Rapidity Distributions

12 Low x 2 ~ (shadowing region) Gluon Shadowing and Nuclear Absorption Data favor weak shadowing and weak nuclear absorption effect (  > 0.92). Need more data to distinguish between different models. Klein,Vogt, PRL 91:142301,2003 Kopeliovich, NP A696:669,2001

13 J/  signal Analysis underway of a data sample (240  b -1 minbias events, 270 TB) Example of Dimuon invariant mass - South arm - Peripheral AuAu Collisions (40-92%) (~30% of data set) Example of Dielectron invariant mass minium bias sample ( < 10% of data set) PHENIX Work in progress J/  Signal in RUN4 Au-Au Collisions

14 Summary and Outlook Charmonium; studied in p-p, d-A, and A-A collisions: - Weak shadowing and absorption has been observed in both central and forward region for J/  production. A modest baseline for Au-Au J/  has been established. * RUN4 has accumulated ~50 times more data (than RUN2) and we already see clear J/  signals! Next run, with Cu-Cu collisions, starts RSN, and is sure to bring much needed info on J/  production.

15 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 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 *as of January Countries; 58 Institutions; 480 Participants*