Meson Measurements and Flavor Dependent Nuclear Suppression at RHICPHENIX

1
Meson Measurements and Flavor Dependent
Nuclear Suppressionat RHIC-PHENIX

• Kotaro M. Kijima
• (Hiroshima University)
• for the PHENIX collaboration

2
Punch line

• A Quark-Gluon-Plasma (QGP) has been created in
  Heavy ion collisions at RHIC
• Now its time to study the detailed properties of
  QGP
• What is expected from ? meson measurements at
  PHENIX experiment?
• Restoration of chiral symmetry
• Elliptic flow v2
• Flavor dependence of Nuclear modification factor

3
RHIC-PHENIX experiment
PHENIX Run Summary

Collision system at RHIC - pp (upto 250GeV)
- dAu/CuCu/AuAu (upto 100AGeV)

• The PHENIX experiment
• Good particle identification
• ??,K?,p,d,e,?, ?
• High resolution
• Wide kinematic coverage
• High rate capability

4
The PHENIX detectorselectron

• zvertex BBC
• Trigger
• MinBias (BBC)
• EMCal RICH trigger (ERT)
• for electrons (pp dAu)
• Tracking DC/PC
• Electron ID
• threshold of cherenkov (RICH)
• Ratio between Energy deposited to EMCal and
  momentum
• Electron is E/p 1

PHENIX acceptance -0.35lt ? lt0.35, 2?90?? for
two arm
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The PHENIX detectors ??, K?, p, p, d, d

• zvertex BBC
• Trigger
• MinBias (BBC)
• ERT trigger (RICH, EMCal)
• for electrons (pp dAu)
• Tracking DC/PC
• Hadron ID(time of flight)
• TOF, EMCal

PHENIX acceptance -0.35lt ? lt0.35, 2x90?? for
two arm
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Restoration of Chiral Symmetry
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Expected mass-modification of Light Vector Meson
(LVM)

• The Braking of the Chiral Symmetry provides
  effective mass of quarks, corresponding to the
  hadron mass.
• This effective mass will vanish in hot or dense
  matter since (partial) restoration of Chiral
  symmetry
• Some models predict the mass modification of LVM
  on hot/dense matter
• Smaller and wider mass is predicted as higher
  temperature

R. Rapp (Nucl. Phys A661(1999) 238c
hadron mass
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Line shape analysis

• The mass-line-shape analysis is the most
  straightforward and direct method
• LVM has hadronic and leptonic decay channels
• Di-lepton channel is good probe
• Leptons carry clean information of LVM in hot
  medium since Lepton does not interact with the
  strong coupled medium

9
Direct measurement of mass states ??ee-

• In pp, the clear peaks of LVM were obtained.

• In AuAu, huge BG from Dalitz and conversion
  electrons
• The PHENIX obtained the mass peak of LVM in AuAu
  collisions
• Resolution is 10MeV

• Line shape analysis in mee is challenging in HIC

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HBD for PHENIX

• Hadron Blind Detector (HBD) has installed in
  PHENIX and and working
• HBD can identify and remove ee- from photonic
  background sources
• Dominant electron source is ?0 Dalitz and ?
  conversions
• HBD reduce background by about 10 to 100

HBD
will be able to analyze mass line shape in HIC
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Branching ratio of ?
??ee ??KK

• Small Q-value to KK-
• m? ? 2 ? mK
• ?ee/?KK may be sensitive to decreasing ? mass
• especially low pT region
• Higher probability decaying in hot/dense matter

mT m0 (GeV/c2)
Hot Matter
Hot Matter
High mT
LVM
Low mT
LVM
??ee and KK is consistent within error bar No
significant modification is observed
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Elliptic flow
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Elliptic flow v2

• significant evidence of hydrodynamic expansion of
  the QGP have been established

• Is elliptic flow development dominantly pre- or
  post-hadronizaion??
• Comparison of the v2 for ? provides unique
  insight
• ?(ss) is expected to have a small hadronic cross
  section with nonstrange hadrons due to
  Okubo-Zweig-Izuka(OZI) rules.
• Such a cross section leads to a relatively large
  mean free pass
• smaller v2 if flow is established in the hadronic
  interacting phase
• Universal scaling of v2/nq ?

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Elliptic flow v2 of ?
KET mT - m
Phys. Rev. Lett. 99, 052301 (2007)

• v2 vs KET
• ? meson follows the flow pattern of the other
  light mesons
• No OZI suppression is observed
• v2/nq vs KET/nq
• universal scaling is working for all particle
  species
• In elliptic flow develops, constituents of the
  flowing medium are NOT ordinary hadrons
• Partnic collectivity reflected quark degree of
  freedom plays a central role for developing the
  transverse expansion!

15
Flavor dependence of Nuclear modification
factor
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Nuclear modification factor in AuAu?0, ?, pp,
direct ?

• ?0 and ? is similar suppression
• The suppression patterns do not have mass
  dependence
• ? ? 4 x ?0
• RAA of proton may be explained by recombination
  model

More detailed analysis needed !
17
Extend to High pT range??KK- measurement

• No Kaon indentified method
• All hadron tracks are selected to reconstruct
  pairs without any identification
• the measurements in pp, CuCu and AuAu have
  been extended up to a pT 7GeV/c, and 5GeV/c in
  dAu

Extended to High pT
Reconstruction efficiency
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Nuclear modification factorin dAu

• ? is not suppressed in dAu.
• In central dAu, collisions, RdAu for ? appears
  to raise above unity
• Cronin Effect is observed
• higher statistic RUN8 dAu data (30?RUN3)
  analysis is ongoing now

pT
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Nuclear modification factorin CuCu

• RAA in CuCu and AuAu are similar at equivalent
  Npart
• Universal Npart scaling is observed

20
Nuclear modification factor in AuAu?0, ?, pp,
direct ?

• The suppression patterns do not have mass
  dependence
• How about ? RAA ?

Meson/Bryon separation ??
21
Nuclear modification factor in AuAu?, ?0, ?,
pp, direct ?

• ? does not follow suppression pattern of meson
• Less suppressed than ?0 and ?
• What makes this difference??

22
Nuclear modification factor in AuAu?, KK-, ?,
?, ?, pp, direct ?

• ? has large errors
• Suppression pattern of K seems to be match to ?

It may suggest s quark is less suppressed than u,
d quark?
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Summary of RAA in AuAu

• At intermediate pT
• Not a mass effect
• Not a baryon/meson effect
• quark flavor dependence !?
• At Higher pT
• Similar suppression for all particles??
• Need mote detailed analysis

Ongoing work in PHENIX Extend of the RAA for
charged Kaons to higher pT Extend of the RAA of
? toward low pT RAA for K0s at high pT
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Summary

• PHENIX has measured ? meson via ee and KK decay
  modes in pp, dAu, CuCu and AuAu collisions at
  ?sNN 200GeV
• Restoration of chiral symmetry
• The peaks of LVM on di-electron mass distribution
  were obtained in HIC, line shape analysis is
  challenging
• No significant modification of branching ratio is
  observed
• Higher statistics with HBD to reject photonic BG,
  will enable measurements in central AuAu
  collisions
• Elliptic flow
• No OZI suppression is observed
• Partonic collectivity plays a central role for
  elliptic flow development
• Flavor dependence of Nuclear modification factor
• Cronin effect may be observed in central dAu
  collisions
• RAA in AuAu and CuCu shows universal Npart
  scaling
• ? is less suppressed than ?0 and ? at
  intermediate pT
• It may suggested s quark is less suppressed than
  u, d quark
• More detailed analysis ongoing now

25
Universidade de São Paulo, Instituto de Física,
Caixa Postal 66318, São Paulo CEP05315-970,
Brazil Institute of Physics, Academia Sinica,
Taipei 11529, Taiwan China Institute of Atomic
Energy (CIAE), Beijing, People's Republic of
China Peking University, Beijing, People's
Republic of China Charles University, Ovocnytrh
5, Praha 1, 116 36, Prague, Czech Republic Czech
Technical University, Zikova 4, 166 36 Prague 6,
Czech Republic Institute of Physics, Academy of
Sciences of the Czech Republic, Na Slovance 2,
182 21 Prague 8, Czech Republic Helsinki
Institute of Physics and University of Jyväskylä,
P.O.Box 35, FI-40014 Jyväskylä, Finland Dapnia,
CEA Saclay, F-91191, Gif-sur-Yvette,
France Laboratoire Leprince-Ringuet, Ecole
Polytechnique, CNRS-IN2P3, Route de Saclay,
F-91128, Palaiseau, France Laboratoire de
Physique Corpusculaire (LPC), Université Blaise
Pascal, CNRS-IN2P3, Clermont-Fd, 63177 Aubiere
Cedex, France IPN-Orsay, Universite Paris Sud,
CNRS-IN2P3, BP1, F-91406, Orsay, France SUBATECH
(Ecole des Mines de Nantes, CNRS-IN2P3,
Université de Nantes) BP 20722 - 44307,
Nantes, France Institut für Kernphysik,
University of Münster, D-48149 Münster,
Germany Debrecen University, H-4010 Debrecen,
Egyetem tér 1, Hungary ELTE, Eötvös Loránd
University, H - 1117 Budapest, Pázmány P. s. 1/A,
Hungary KFKI Research Institute for Particle and
Nuclear Physics of the Hungarian Academy of
Sciences (MTA KFKI RMKI), H-1525 Budapest
114, POBox 49, Budapest, Hungary Department of
Physics, Banaras Hindu University, Varanasi
221005, India Bhabha Atomic Research Centre,
Bombay 400 085, India Weizmann Institute, Rehovot
76100, Israel Center for Nuclear Study, Graduate
School of Science, University of Tokyo, 7-3-1
Hongo, Bunkyo, Tokyo 113-0033,
Japan Hiroshima University, Kagamiyama,
Higashi-Hiroshima 739-8526, Japan KEK, High
Energy Accelerator Research Organization,
Tsukuba, Ibaraki 305-0801, Japan Kyoto
University, Kyoto 606-8502, Japan Nagasaki
Institute of Applied Science, Nagasaki-shi,
Nagasaki 851-0193, Japan RIKEN, The Institute of
Physical and Chemical Research, Wako, Saitama
351-0198, Japan Physics Department, Rikkyo
University, 3-34-1 Nishi-Ikebukuro, Toshima,
Tokyo 171-8501, Japan Department of Physics,
Tokyo Institute of Technology, Oh-okayama,
Meguro, Tokyo 152-8551, Japan Institute of
Physics, University of Tsukuba, Tsukuba, Ibaraki
305, Japan Chonbuk National University, Jeonju,
Korea Ewha Womans University, Seoul 120-750,
Korea Hanyang University, Seoul 133-792,
Korea KAERI, Cyclotron Application Laboratory,
Seoul, South Korea Korea University, Seoul,
136-701, Korea Myongji University, Yongin,
Kyonggido 449-728, Korea System Electronics
Laboratory, Seoul National University, Seoul,
South Korea Yonsei University, IPAP, Seoul
120-749, Korea IHEP Protvino, State Research
Center of Russian Federation, Institute for High
Energy Physics, Protvino, 142281,
Russia Joint Institute for Nuclear Research,
141980 Dubna, Moscow Region, Russia Russian
Research Center "Kurchatov Institute", Moscow,
Russia PNPI, Petersburg Nuclear Physics
Institute, Gatchina, Leningrad region, 188300,
Russia Saint Petersburg State Polytechnic
University, St. Petersburg, Russia Skobeltsyn
Institute of Nuclear Physics, Lomonosov Moscow
State University, Vorob'evy Gory, Moscow
119992, Russia Department of Physics, Lund
University, Box 118, SE-221 00 Lund, Sweden
14 Countries 70 Institutions
July 2009
Thank you !!
Abilene Christian University, Abilene, TX 79699,
U.S. Collider-Accelerator Department, Brookhaven
National Laboratory, Upton, NY 11973-5000,
U.S. Physics Department, Brookhaven National
Laboratory, Upton, NY 11973-5000, U.S. University
of California - Riverside, Riverside, CA 92521,
U.S. University of Colorado, Boulder, CO 80309,
U.S. Columbia University, New York, NY 10027 and
Nevis Laboratories, Irvington, NY 10533,
U.S. Florida Institute of Technology, Melbourne,
FL 32901, U.S. Florida State University,
Tallahassee, FL 32306, U.S. Georgia State
University, Atlanta, GA 30303, U.S. University of
Illinois at Urbana-Champaign, Urbana, IL 61801,
U.S. Iowa State University, Ames, IA 50011,
U.S. Lawrence Livermore National Laboratory,
Livermore, CA 94550, U.S. Los Alamos National
Laboratory, Los Alamos, NM 87545, U.S. University
of Maryland, College Park, MD 20742,
U.S. Department of Physics, University of
Massachusetts, Amherst, MA 01003-9337, U.S.
Morgan State University, Baltimore, MD 21251,
U.S. Muhlenberg College, Allentown, PA
18104-5586, U.S. University of New Mexico,
Albuquerque, NM 87131, U.S. New Mexico State
University, Las Cruces, NM 88003, U.S. Oak Ridge
National Laboratory, Oak Ridge, TN 37831,
U.S. Department of Physics and Astronomy, Ohio
University, Athens, OH 45701, U.S. RIKEN BNL
Research Center, Brookhaven National Laboratory,
Upton, NY 11973-5000, U.S. Chemistry Department,
Stony Brook University, Stony Brook, SUNY, NY
11794-3400, U.S. Department of Physics and
Astronomy, Stony Brook University, SUNY, Stony
Brook, NY 11794, U.S. University of Tennessee,
Knoxville, TN 37996, U.S. Vanderbilt University,
Nashville, TN 37235, U.S.
26
Back up
27
ERT (EICH EMC Trigger)
28
The invariant mass spectra for f mesons
f-gt ee- dAu
f-gtee- AuAu
f-gt ee- pp
f
f
f-gtKK- (double PID) dAu
f-gt KK- (double PID) AuAu
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The invariant mass spectra for f mesons
f-gtKK- (single PID) pp
f-gtKK- (no PID) pp
f-gtKK- (no PID) AuAU
f-gtKK- (no PID) dAu
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RAA in AuAu
RPC79, 064903 (STAR)
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HBD