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Diagnosing energy loss: PHENIX results on high-p T hadron spectra. Baldo Sahlmüller, University of Münster for the PHENIX collaboration. A+A. p+p. Physics Motivation: Why high-p T ?. At high energy: hard scattering cross section large Measuring high p T particle yields: - PowerPoint PPT Presentation
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Diagnosing energy loss: PHENIX results on high-pT hadron spectra
Baldo Sahlmüller, University of Münster
for the PHENIX collaboration
Baldo Sahlmüller Quark Matter 2006 2
Physics Motivation:Why high-pT?
• At high energy: hard scattering cross section large
• Measuring high pT particle yields:– Initial yields and pT distributions can be
predicted from p+p measurements + pQCD + cold nuclear effects
– Deviations can be attributed to the medium formed in A+A collisions
• High pT particles (leading particles of jets) as ,0 can be measured in large BGs (dNch/d ~ 700)
• Quantification with nuclear modification factor:
A+A
p+p
Baldo Sahlmüller Quark Matter 2006 3
What we already know
• System size dependence at 200 GeV– Suppression up to high pT
– Consistent with dNg/dy = 1200 (Au+Au) and dNg/dy = 370 (Cu+Cu)
Questions: What happens at lower energies?
Connection towards SPS energies?
• Similar suppression for similar Npart
- Consistent with pure density and path length dependence- also: taking into account shape of nuclei
Baldo Sahlmüller Quark Matter 2006 4
The PHENIX Experiment
• Measurement of , 0 via decay
• Decay ’s are measured in EMCal– 2 sectors PbGl, 6 sectors
PbSc in 2 arms– Covers ||<0.35, =180°– Granularity fine enough to
measure 0’s up to pT ~ 25 GeV/c
, 0
Baldo Sahlmüller Quark Matter 2006 5
Diagnosing Heavy Ion Collisions
So far: status of investigating energy loss with high pT particle production; dependence on:
• Centrality OK• pT OK• System size (OK)
=> Next step: energy dependence
Baldo Sahlmüller Quark Matter 2006 6
200 GeV
Baldo Sahlmüller Quark Matter 2006 7
T
The p+p Reference
• Measurement at 200 GeV
•nucl-ex/0610036
0
=> See poster by A. Bazilevsky!
Baldo Sahlmüller Quark Matter 2006 8
nucl-ex/0610036
Initial State Effects?
• New PHENIX paper on centrality dependence of 0+ in d+Au at 200 GeV
• d+Au as collision system to look for initial state effects
=> no strong initial state effects
nucl-ex/0610036
Baldo Sahlmüller Quark Matter 2006 9
Au+Au at 200 GeV
• data from RHIC run 2004
=> See poster by M.L. Purschke!
Baldo Sahlmüller Quark Matter 2006 10
RAA at 200 GeV
• in Au+Au
=> Suppression by a factor of 5 in central events
Baldo Sahlmüller Quark Matter 2006 11
RAA at 200 GeV
• Direct , 0 and in Au+Au– Direct RAA with measured p+p reference!
=> RAA of and 0 consistent, both show suppression
=> RAA of is smaller than 1 at very high pT
0-10% central events
Baldo Sahlmüller Quark Matter 2006 12
62.4 GeV
Baldo Sahlmüller Quark Matter 2006 13
The p+p Reference
• p+p parameterization at 62.4 GeV: Fit to existing (ISR) data at similar energies (D.d'Enterria. J.Phys.G31, S491 (2005))
Baldo Sahlmüller Quark Matter 2006 14
The p+p Reference
• Problem: data sets inconsistent => large error
new important RHIC measurement in 2006 Analysis still ongoing
Baldo Sahlmüller Quark Matter 2006 15
Au+Au at 62.4 GeV
• Au+Au 0:– Suppression in central
events– Important: influence of
error in p+p reference!– Theoretical curve:
Vitev nucl-th/0404052
dNg/dy = 650-800
Baldo Sahlmüller Quark Matter 2006 16
Spectra in Cu+Cu at 62.4 GeV
0
=> See poster by T. Sakaguchi!
Baldo Sahlmüller Quark Matter 2006 17
RAA in Cu+Cu at 62.4 GeV
Cu+Cu0:• centrality dependent• Important: Influence of
error in p+p reference!• Centrality dependent
behavior• Enhancement in
peripheral events
• RAA smaller in central events
Baldo Sahlmüller Quark Matter 2006 18
RAA vs. Npart at 62.4 GeV
• RAA integrated at high pT
• Again: Large normalization uncertainty from p+p reference
• RAA smaller towards higher Npart
• Same theoretical model as for 200 GeV data consistent within errors
Baldo Sahlmüller Quark Matter 2006 19
22.4 GeV
Baldo Sahlmüller Quark Matter 2006 20
The p+p Reference
• p+p parameterization at 22.4 GeV: Fit to existing data at similar energies (D.d'Enterria. J.Phys.G31, S491 (2005))
Baldo Sahlmüller Quark Matter 2006 21
0 at 22.4 GeV
• Towards SPS energies: Cu+Cu at 22.4 GeV
Little centrality dependence
Baldo Sahlmüller Quark Matter 2006 22
SPS and RHIC
• Same behavior for similar Npart (63 at WA98, 67.8 at PHENIX)
Blattnig parameterization used for WA98 data (S. Blattnig et. al., Phys.Rev. D62 (2000) 094030 / D. D’Enterria, Phys. Lett. B 596 (2004) 32))
Baldo Sahlmüller Quark Matter 2006 23
RAA at Different Energies
• Comparison of 0 in Cu+Cu at 200, 62.4, and 22.4 GeV
– Measured the same collision species over a broad energy range
• Suppression gets larger with higher energies
Baldo Sahlmüller Quark Matter 2006 24
Particle Ratio
Baldo Sahlmüller Quark Matter 2006 25
Ratio in Au+Au
• Ratio /0 for different centralities in comparison with PYTHIA prediction
PYTHIA works very well in describing the ratio in heavy-ion collisions
Possible conclusion (for high pT): Suppression at partonic level, fragmentation outside medium
Baldo Sahlmüller Quark Matter 2006 26
Ratio in p+p and Cu+Cu
• Ratio0
• Approximately 0.5 at high pT
• First PHENIX measurement at 62.4 GeV
p+p
Cu+Cu
nucl-ex/0611006
Baldo Sahlmüller Quark Matter 2006 27
“World” data
All PHENIX data consistent with world data Ratio shows no obvious energy dependence
Baldo Sahlmüller Quark Matter 2006 28
Data vs. Theory?
Baldo Sahlmüller Quark Matter 2006 29
Comparing to Theories
How probable is a certain parameter in theory?
Theory: Loizides,hep-ph/0608133v2
10%)ty (Probabili
fm/cGeV 24ˆ6 22
>
≤≤ q
Taking into account errors of measurement (for a certain theory parameter):
1. vary points within 4 RMS of correlated errors, find most probable point
2. calculate probability for large number of randomly picked sets of correlated and uncorrelated errors
3. see how many of these are worse than point from step 1
Baldo Sahlmüller Quark Matter 2006 30
Comparing to Theories
10%)ty (Probabili
fm/cGeV 00021000 22
>
≤≤ dydNg
another compilation…
Theory: I. Vitev,Phys.Lett.B639:38-45,2006
Baldo Sahlmüller Quark Matter 2006 31
Comparing to Theories
and another compilation…
10%)ty (Probabili
1600600
>
≤≤ dydNg
Theory: William Horowitz
Baldo Sahlmüller Quark Matter 2006 32
Summary
• Au+Au at 200 GeV– New measurement up to pT = 15 GeV/c– Similar suppression patterns of and0
• Cu+Cu at 62.4 GeV– Strong 0 enhancement in peripheral events– RAA gets smaller in central events
• Cu+Cu at 22 GeV– No significant centrality dependence in 0 production– Consistent with SPS results at 17.3 GeV
• Ratio 0
– Ratio 0 similar for different collision systems and energies• Results in Cu+Cu and Au+Au consistent with partonic energy
loss in the medium, fragmentation in the vacuum
Baldo Sahlmüller Quark Matter 2006 33
Finally: Back to the List
So far: status of investigating energy loss with high pT particle production; dependence on:– Centrality OK– pT OK– System size (OK)
Baldo Sahlmüller Quark Matter 2006 34
Finally: Back to the List
Now: status of investigating energy loss with high pT particle production; dependence on:– Centrality OK– pT OK– System size OK– Energy OK
13 Countries; 62 Institutions; 550 Participants*
*as of March 2005
• Lund University, Lund, Sweden• Abilene Christian University, Abilene, Texas, USA• Brookhaven National Laboratory (BNL), Upton, NY 11973, USA• University of California - Riverside (UCR), Riverside, CA 92521, USA• University of Colorado, Boulder, CO, USA• Columbia University, Nevis Laboratories, Irvington, NY 10533, USA• Florida Institute of Technology, Melbourne, FL 32901, USA• Florida State University (FSU), Tallahassee, FL 32306, USA• Georgia State University (GSU), Atlanta, GA, 30303, USA• University of Illinois Urbana-Champaign, Urbana-Champaign, IL, USA• Iowa State University (ISU) and Ames Laboratory, Ames, IA 50011, USA• Los Alamos National Laboratory (LANL), Los Alamos, NM 87545, USA• Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA• University of New Mexico, Albuquerque, New Mexico, USA• New Mexico State University, Las Cruces, New Mexico, USA• Department of Chemistry, State University of New York at Stony Brook (USB),
Stony Brook, NY 11794, USA• Department of Physics and Astronomy, State University of New York at Stony
Brook (USB), Stony Brook, NY 11794, USA• Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA• University of Tennessee (UT), Knoxville, TN 37996, USA• Vanderbilt University, Nashville, TN 37235, USA
• University of São Paulo, São Paulo, Brazil• Academia Sinica, Taipei 11529, China• China Institute of Atomic Energy (CIAE), Beijing, P. R. China• Peking University, Beijing, P. R. China• Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, 12116
Prague, Czech Republic• Czech Technical University, Faculty of Nuclear Sciences and Physical
Engineering, Brehova 7, 11519 Prague, Czech Republic• Institute of Physics, Academy of Sciences of the Czech Republic, Na
Slovance 2, 182 21 Prague, Czech Republic• Laboratoire de Physique Corpusculaire (LPC), Universite de Clermont-
Ferrand, 63 170 Aubiere, Clermont-Ferrand, France• Dapnia, CEA Saclay, Bat. 703, F-91191 Gif-sur-Yvette, France• IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406 Orsay, France• Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de
Saclay, F-91128 Palaiseau, France• SUBATECH, Ecòle des Mines at Nantes, F-44307 Nantes France• University of Muenster, Muenster, Germany• KFKI Research Institute for Particle and Nuclear Physics at the Hungarian
Academy of Sciences (MTA KFKI RMKI), Budapest, Hungary• Debrecen University, Debrecen, Hungary• Eövös Loránd University (ELTE), Budapest, Hungary• Banaras Hindu University, Banaras, India• Bhabha Atomic Research Centre (BARC), Bombay, India• Weizmann Institute, Rehovot, 76100, Israel• Center for Nuclear Study (CNS-Tokyo), University of Tokyo, Tanashi, Tokyo
188, Japan• Hiroshima University, Higashi-Hiroshima 739, Japan• KEK - High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba,
Ibaraki 305-0801, Japan• Kyoto University, Kyoto, Japan• Nagasaki Institute of Applied Science, Nagasaki-shi, Nagasaki, Japan• RIKEN, The Institute of Physical and Chemical Research, Wako, Saitama 351-
0198, Japan• RIKEN – BNL Research Center, Japan, located at BNL• Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima,
Tokyo 171-8501, Japan• Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan• University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi Ibaraki-ken 305-8577,
Japan• Waseda University, Tokyo, Japan• Cyclotron Application Laboratory, KAERI, Seoul, South Korea• Kangnung National University, Kangnung 210-702, South Korea• Korea University, Seoul, 136-701, Korea• Myong Ji University, Yongin City 449-728, Korea• System Electronics Laboratory, Seoul National University, Seoul, South
Korea• Yonsei University, 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 (JINR-Dubna), Dubna, Russia• Kurchatov Institute, Moscow, Russia• PNPI, Petersburg Nuclear Physics Institute, Gatchina, Leningrad region,
188300, Russia• Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State
University, Vorob'evy Gory, Moscow 119992, Russia• Saint-Petersburg State Polytechnical Univiversity, Politechnicheskayastr, 29,
St. Petersburg, 195251, Russia
Map No. 3933 Rev. 2 UNITED NATIONSAugust 1999
Department of Public InformationCartographic Section
Baldo Sahlmüller Quark Matter 2006 36
Related Talks and Posters
• Talks– 2.2.5 V. S. Pantuev PHENIX measurements of reaction plane dependence of high-pT photons and pions in
Au+Au collisions– 3.1.2 Yu. Riabov Measurement of leptonic and hadronic decays of and mesons at RHIC by PHENIX – 3.2.2 M. Konno High-pT Identified Hadron Production in Au+Au and Cu+Cu Collisions at RHIC-PHENIX– 3.3.1 T. Isobe Systematic Study of High-pT Direct Photon Production with the PHENIX
Experiment at RHIC
• Posters– 1.14 M. L. Purschke Measurement of pT distributions in SNN =200 GeV Au-Au collisions at RHIC-
PHENIX– 1.18 V. Ryabov Measurements of the multi-hadron decays of and mesons in heavy ion collisions at
SNN= 200 GeV in the PHENIX experiment at RHIC– 2.38 M. Shimomura Measurement of Azimuthal Anisotropy for High-pT Charged Hadron at RHIC-
PHENIX– 2.50 T. Sakaguchi System size and energy dependence of high-pT hadron production measured with the
PHENIX experiment at RHIC– 2.51 D. Winter High-pT π0 production with respect to the reaction plane in SNN = 200 GeV Au+Au
collisions at PHENIX