J/ measurements at RHIC/PHENIX

David Silvermyr, ORNL

for the PHENIX collaboration

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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

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Create very high temperature and density matteras existed ~10 sec after the Big Banginter-hadron distances comparable to that in neutron starscollide heavy ions to achieve maximum volume

Study the hot, dense mediumis thermal equilibrium reached?transport properties? equation of state?do the nuclei dissolve into a quark gluon plasma?

Collide Au + Au ions at high energys = 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

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• ’’Onia’’ production– Leading order at low x

= ’’gluon fusion’’

• Sensitive to:

Final stateParton energy loss in the hot & dense medium ?Thermal enhancement ?Flow ?

Initial stateParton distribution functionspT broadeningParton energy loss in the initial state ?Polarization ?

J/or

+ feed-down (e.g. B or c-> J/)

Heavy Flavor Production

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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

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• 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

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PHENIX

Two central arms for measuring hadrons, photons and electrons

Two forward arms for measuring muons

Event characterization detectors in middle

electrons: central armselectron measurement in

range: || 0.35

p 0.2 GeV/c

muons: forward armsmuon measurement in range:

1.2 < || < 2.4

p 2 GeV/c

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Year Ions sNN Luminosity Detectors J/

2000[Run-1] Au-Au 130 GeV 1 b-1 Central

(electrons) 0

2001 Au-Au 200 GeV 24 b-1Central 13 + 0 [1]

2002[Run-2] p-p 200 GeV 0.15 pb-1 + 1 muon arm 46 + 66 [2]

2002 d-Au 200 GeV 2.74 nb-1Central 300+800+600

2003[Run-3] p-p 200 GeV 0.35 pb-1 + 2 muon arms 100+300+120

2004[Run-4] Au-Au 200 GeV

62 GeV~240 ub-1

~9 ub-1

Central+ 2 muon arms

?[thousands]

?

[1] nucl-ex/0305030, Phys. Rev. C 69, 014901 (2004). [2] hep-ex/0307019, Phys. Rev. Lett. 92, 051802 (2004)

RHIC History

NJ/ ~= 10Run

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• 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 X2 (in gold) ~ 0.09– Central (y ~ 0) : intermediate X2 ~ 0.02– North (y > 1.2) : small X2 (in gold) ~ 0.003

X1 X2

J/ inNorthy > 0

X1 X2

J/ inSouthy < 0

rapidity y

From Eskola, Kolhinen, VogtNucl. Phys. A696 (2001) 729-746.

Example of predicted gluon shadowing in d+Augluons in Pb / gluons in p

X

AntiShadowing

Shadowing

J/ +-/e+e- for dAu & ppNorth Muon ArmSouth Muon Arm

d Au

Central Arm

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389 J/ψ’s~ 100 MeV

J/ψ e+e- |y|<0.35J/ψ +- 1.2<|y|<2.4

+-

±±

780 J/ψ’s ~ 165 MeV

North ArmdAu

J/ +-/e+e- for dAu

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In RUN3, we accumulated ~300nb-1 p-p and ~3nb-1 d-Au collisions.

J/ Rapidity Distributions

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Low x2 ~ 0.003(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

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J/ signal

• Analysis underway of a data sample (240 b-1minbias 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

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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.

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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 PauloChina Academia Sinica, Taipei, Taiwan China Institute of Atomic Energy, Beijing Peking University, BeijingFrance 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, NantesGermany University of Münster, MünsterHungary Central Research Institute for Physics (KFKI), Budapest Debrecen University, Debrecen Eötvös Loránd University (ELTE), Budapest India Banaras Hindu University, Banaras Bhabha Atomic Research Centre, BombayIsrael Weizmann Institute, RehovotJapan 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, SeoulRussia 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. PetersburgSweden Lund University, Lund

*as of January 2004

12 Countries; 58 Institutions; 480 Participants*