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T.C.Awes, ORNL
Centrality Dependence of 0 Production in d+Au Collisions
T.C. Awes, ORNLFor the PHENIX Experiment
Fall DNP Tucson, AZ, October 30, 2003
T.C.Awes, ORNL
Quenching of Hard Scattered Partons
• In the presence of a dense strongly interacting medium, hard scattered partons will suffer soft interactions losing energy before fragmenting into jet of hadrons (“Jet Quenching”)
• Quenching is observed, but could it be due to initial state effect? (“Gluon Saturation”)
Hadrons
Leading Particle
Leading Particle
Hadrons
q,gq,g
Hadrons
Leading Particle
Leading Particle
Hadrons
q,gq,g
• Reference case: d+Au No produced medium.
T.C.Awes, ORNL
RAuAu : High PT 0 Suppression to at least 10 GeV/c
PRL 91 (2003) 072301
Binary scaling
Participant scaling
Factor ~4-5
pp
AuAubinaryAuAuAA Yield
NYieldR
/ ⟩⟨=
Large suppression in central AuAu - close to participant scaling at high PT
Peripheral AuAu - consistent with Ncoll scaling (large systematic error)
T.C.Awes, ORNL
Cronin Effect:(RAA>1) Charged hadrons vs. 0
• Different behavior between 0 and charged at pT = 1.5 - 5.0 GeV/c!
• d+Au data suggests flavor dependent Cronin effect.
d+Au
Au+Au
PHENIXPRL 91 072303 (2003) nucl-ex/0306021
Particle ID is important!
d+Au: Cronin Effect (RdA>1): Initial Multiple Collisions broaden PT
spectrum
T.C.Awes, ORNL
PHENIX Electromagnetic Calorimeter
PbSc• Highly segmented lead scintillatorsampling Calorimeter• Module size: 5.5 cm x 5.5 cm x 37 cmPbGl•Highly segmented lead glassCherenkov Calorimeter• Module size: 4 cm x 4 cm x 40 cm
Two Technologies - very important for systematic error understanding!Differences:•Different response to hadrons•Different corrections to get linearenergy response•Different shower overlap corrections
T.C.Awes, ORNL
d+Au Collision Centrality Determination
•Extract Ncoll and Npart based on Glauber model.
South Blick von der Seite North
BB
MuTr
MuID MuID
ZDC NorthZDC South
MVD
Central Magnet
North Muon Magnet
South Muon MagnetPeripheral
Central
Sum BBC Charge -> Multiplicity
Au d
• 0-20 % : 15.0 ± 1.0
• 20-40 % : 10.4 ± 0.7
• 40-60 % : 6.9 ± 0.6
• 60-88 % : 3.2 ± 0.3
Centrality <Ncoll>
• Centrality selection : Beam-Beam Counter South (Au) (BBC, ||=3~4)
T.C.Awes, ORNL
Centrality Dependence of d+Au Spectra
• Combined PbSc and PbGlresults
•0 Yields measured to ~10 GeV/c
T.C.Awes, ORNL
RdAu PbGl and PbSc Comparison
T.C.Awes, ORNL
RdAu 0 Centrality Dependence
• Weak increase with centrality (Cronin effect)
• d+Au centrality dependence opposite to Au+Au
• Strongly suggests Au+Au suppression is due to effect of dense produced matter
T.C.Awes, ORNL
RdAu 0 Centrality Dependence vs. Theory
Rd
Au
Nucl-th/0308029, Accardi and GyulassySession CC.002 FridayAM.
T.C.Awes, ORNL
and Charged Comparison (Ratio to fit)
F.Matathias, CC-7, Friday AM
T.C.Awes, ORNL
Central to peripheral
T.C.Awes, ORNL
Summary and Conclusions
• A strong suppression of 0 production is observed in central Au+Au collisions at RHIC possibly due to parton energy loss in the medium (result is not conclusive in itself).
• The 0 production in d+Au collisions shows no strong suppression at high-PT but rather an enhancement which increases with centrality (Cronin effect).
• Strongly indicative that the suppression effect in central Au+Au is due to the created QCD medium.
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 Georgia State University, Atlanta, GA University of Illinois 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, Ecole Polytechnique, CNRS-IN2P3, Palaiseau SUBATECH, Ecole des Mines de Nantes, CNRS-IN2P3, Univ. 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 University of Tokyo, Bunkyo-ku, Tokyo 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
12 Countries; 57 Institutions; 460 Participants
T.C.Awes, ORNL
BACKUP SLIDES
T.C.Awes, ORNL
RAA vs. RdA for Identified 0
d+Au
Au+Au
The dAu results (initial state effects only) suggest that the created medium is responsible for high pT suppression in Au+Au.
Neutral pions are measured with 2 independent Calorimeters – PbSc and PbGl: Consistency check.
PHENIX, PRL91 (2003) 072303.
T.C.Awes, ORNL
Centrality Dependence of RAA
More central collisions D.Kharzeev, E.Levin, L.McLerranhep-ph/0210332
PRL 91 (2003) 072301
The suppression increases smoothly with centrality - approximate Npart scaling.
Centrality dependence similar topredictions of Color Glass Condensate(AKA Gluon Saturation)-Suggests Initial state effect!?!
-Need p+Au (d+Au)
T.C.Awes, ORNL
Centrality Dependence
• Opposite centrality evolution of Au+Au compared to d+Au control.• Initial state enhancement (“Cronin effect”) in d+Au is suppressed
by final state effect in Au+Au. • Notice difference between 0 and h++h- .
Au + Au d + Au Control
Preliminary DataFinal Data
T.C.Awes, ORNL
Data vs Theory : 0
PHENIX Preliminary
0 d+Au (minbias) 200 GeV
0 Au+Au (0-5%) 200 GeV
Au+Au: I. Vitev and M. Gyulassy, hep-ph/0208108, to appear in Nucl. Phys. A; M. Gyulassy, P. Levai and I. Vitev, Nucl. Phys. B 594, p. 371 (2001).
Shadowing
Anti-shadowing
d+Au: I. Vitev, nucl-th/0302002 and private communication.
Energy loss + Shadowing + Cronin explains both Au+Au and d+Au!
Can dAu and AuAu centrality dependence also be explained?