Diagnosing energy loss: PHENIX results on high-pT hadron spectra Baldo Sahlmüller, University of Münster for the PHENIX collaboration.
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Transcript Diagnosing energy loss: PHENIX results on high-pT hadron spectra Baldo Sahlmüller, University of Münster for the PHENIX collaboration.
Diagnosing energy loss: PHENIX results
on high-pT hadron spectra
Baldo Sahlmüller, University of Münster
for the PHENIX collaboration
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 h,p0 can be measured in large
BGs (dNch/dh ~ 700)
• Quantification with nuclear modification
factor:
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p+p
A+A
2
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)
• Similar suppression for similar Npart
- Consistent with pure density and path
length dependence
- also: taking into account shape
of nuclei
Questions: What happens at lower energies?
Connection towards SPS energies?
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The PHENIX Experiment
• Measurement of h, p0
via gg decay
• Decay g’s are measured
in EMCal
– 2 sectors PbGl, 6 sectors
PbSc in 2 arms
– Covers |h|<0.35, f=180°
– Granularity fine enough to
measure p0’s up to pT ~
25 GeV/c
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h, p0
4
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
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200 GeV
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The p+p Reference
• Measurement at 200 GeV
•nucl-ex/0610036
h
p0
T
=> See poster by A. Bazilevsky!
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Initial State Effects?
• New PHENIX paper on centrality
dependence of p0+h in d+Au at
200 GeV
• d+Au as collision system to look
for initial state effects
nucl-ex/0610036
nucl-ex/0610036
=> no strong initial state effects
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Au+Au at 200 GeV
•
h data from RHIC run 2004
=> See poster by M.L. Purschke!
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RAA at 200 GeV
• h in Au+Au
=> Suppression by a factor of 5 in central events
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RAA at 200 GeV
• Direct g, p0 and h in Au+Au
– Direct g RAA with measured p+p reference!
0-10% central events
=> RAA of h and p0 consistent, both show suppression
=> RAA of g is smaller than 1 at very high pT
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62.4 GeV
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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))
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The p+p Reference
• Problem: data sets inconsistent => large error
new important RHIC measurement in 2006
Analysis still ongoing
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Au+Au at 62.4 GeV
• Au+Au p0:
– Suppression in central
events
– Important: influence of
error in p+p reference!
– Theoretical curve:
Vitev nucl-th/0404052
dNg/dy = 650-800
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Spectra in Cu+Cu at 62.4 GeV
h
p0
=> See poster by T. Sakaguchi!
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RAA in Cu+Cu at 62.4 GeV
Cu+Cu p0:
• centrality dependent
• Important: Influence of
error in p+p reference!
• Centrality dependent
behavior
• Enhancement in
peripheral events
• RAA smaller in central
events
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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
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22.4 GeV
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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))
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p0 at 22.4 GeV
• Towards SPS
energies: Cu+Cu at
22.4 GeV
Little centrality dependence
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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))
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RAA at Different Energies
• Comparison of p0 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
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Particle Ratio
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Ratio in Au+Au
• Ratio h/p0 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
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Ratio in p+p and Cu+Cu
• Ratio h/p0
• Approximately 0.5 at high pT
• First PHENIX h measurement
at 62.4 GeV
Cu+Cu
nucl-ex/0611006
p+p
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“World” data
All PHENIX data consistent with world data
Ratio shows no obvious energy dependence
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Data vs. Theory?
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Comparing to Theories
How probable is a certain parameter in theory?
Theory: Loizides,
hep-ph/0608133v2
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
6 qˆ 24 GeV 2 /c 2 fm
(Probabili ty 10%)
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Comparing to Theories
another compilation…
Theory: I. Vitev,
Phys.Lett.B639:38-45,2006
1000
dNg
2000 GeV 2 /c 2 fm
dy
(P robability 10%)
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Comparing to Theories
and another compilation…
Theory: William Horowitz
600
dNg
1600
dy
(P robability 10%)
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Summary
• Au+Au at 200 GeV
– New h measurement up to pT = 15 GeV/c
– Similar suppression patterns of h and p0
• Cu+Cu at 62.4 GeV
– Strong p0 enhancement in peripheral events
– RAA gets smaller in central events
• Cu+Cu at 22 GeV
– No significant centrality dependence in p0 production
– Consistent with SPS results at 17.3 GeV
• Ratio h/p0
– Ratio h/p0 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
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Finally: Back to the List
So far: status of investigating energy loss
with high pT particle production; dependence
on:
– Centrality
– pT
– System size
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OK
OK
(OK)
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Finally: Back to the List
Now:
status of investigating energy loss
with high pT particle production; dependence
on:
–
–
–
–
Centrality
pT
System size
Energy
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OK
OK
OK
OK
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University o f S‹ o Paulo, S‹ o Paulo, Brazil
Academia Sinica, Taipei 11529, China
China Institute o f Atomic Energy (CIAE ), Beijing, P. R. China
Peking University, Beij ing, P. R. China
Charles U niversity, Faculty o f Mathematics and Physics, Ke Karlovu 3, 12116
Prague, Czech Republic
Czech Technical University, Faculty of Nuclear Sciences and Physical
Engineering, Brehova 7, 11519 P rague, Czech Republic
Institute o f Physics, Academy of Sciences of the Czech Republic, Na
Slovance 2, 182 21 P rague, Czech Republic
Laboratoire de Ph ysique C orpusculaire (LPC), Universite de C lermontFerrand, 63 170 Aubiere, Clermont-Ferrand, France
Dapnia, CEA Sa clay, Bat. 703, F-91191 Gif-sur-Yvette, France
IPN-Orsay, Universite Paris Sud, CNRS-IN2P3, BP1, F-91406 O rsay, France
Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS-IN2P3, Route de
Saclay, F-91128 P alaiseau, France
SUBATECH, Ecle des M ines a t Nantes, F-44307 Nantes F rance
University o f Muenster, Muenster, Germany
KFKI Research Institute for Particle a nd Nuclear Physics at the Hungarian
Academy of Sciences (MTA KFKI RMKI), B udapest, Hungary
Debrecen University, Debrecen, Hungary
Evs Lor‡nd University (ELTE), Budapest, Hungary
Banaras H indu University, Banaras, India
Bhabha A tomic Research Centre (BARC), Bombay, India
W eizmann Institute, Rehovot, 76100, Israel
Center for Nuclear Study (CNS-Tokyo), Univ ersity o f Tokyo, Tanashi, Tokyo
188, Japan
Hiroshima University, Higashi-Hiroshima 739, Japan
KEK - High Energy A ccelerator Research Organization, 1-1 Oho, Tsukuba,
Ibaraki 305-0801, Japan
Kyoto University, Kyoto, Japan
Nagasaki Institute o f Applied Science, Nagasaki-shi, Nagasaki, Japan
RIKEN, The Institute o f Phys ical and Chemical Research, Wako, Saitama 3 510198, Japan
RIKEN Š BNL Research Center, Japan, located at BNL
Physics D epartment, Rikkyo U niversity, 3-34-1 Nishi-Ikebukuro, Toshima,
Tokyo 171-8501, Japan
Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan
University o f Tsukuba, 1-1-1 Tennodai, Tsukuba-shi Ibaraki-ken 305-8577,
Japan
W aseda U niversity, Tokyo , Japan
Cyclotron Application Laboratory, KAERI, Seoul, South Korea
Kangnung National University, Kangnung 210-702, South Korea
Korea U niversity, Seoul, 136-701, Korea
Myong Ji University, Yongin City 449-728, Korea
System E lectronics 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 P hys ics", 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 Go ry, Moscow 1 19992, Russia
Saint-Petersburg State P olytechnical Univ iv ersity, Politechnicheskayastr, 29,
St. Petersburg, 195251, Russia
Map No. 3933 Re
August 1999
v. 2 UNITE D N ATIONS
Department of P ublic Informat ion
Cartographi c Section
13 Countries; 62 Institutions; 550 Participants*
Lund University, Lund, Sweden
Abilene Christian University, Abilene, Texas, USA
Brookhaven National Laboratory (BNL), Upton, NY 11973, USA
University o f California - Riverside (UCR), Riverside, CA 92521, USA
University o f 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 o f Illinois Urbana-Champaign, Urbana-Champaign, IL, USA
Iowa State University (ISU) and Ames Laboratory, Am es, IA 50011, USA
Los Alamos National Laboratory (LANL), Los Alamos, NM 87545, USA
Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA
University o f New Mexico, Albuquerque, New M exico, USA
New Me xico State University, Las Cruces, New Mexico, USA
Department of Chemistry, State University of New Y ork at Stony B rook (USB),
Stony B rook, NY 11794, USA
Department of Phys ics and Astronomy, State University o f New York at Stony
Brook (USB), Stony Brook, NY 11794, USA
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA
University o f Tennessee (UT), Knoxville, TN 37996, USA
Vanderbilt University, Nashville, T N 37235, USA
*as of March 2005
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 w and f mesons at RHIC by
PHENIX
3.2.2 M. Konno High-pT Identified Hadron Production in Au+Au and Cu+Cu Collisions at RHICPHENIX
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 h pT distributions in SNN =200 GeV Au-Au collisions at
RHIC-PHENIX
1.18 V. Ryabov Measurements of the multi-hadron decays of w and f 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 RHICPHENIX
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
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