Diagnosing energy loss: PHENIX results on high-pT hadron spectra Baldo Sahlmüller, University of Münster for the PHENIX collaboration.
Download ReportTranscript 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: Baldo Sahlmüller Quark Matter 2006 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? Baldo Sahlmüller Quark Matter 2006 3 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 Baldo Sahlmüller Quark Matter 2006 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 Baldo Sahlmüller Quark Matter 2006 5 200 GeV Baldo Sahlmüller Quark Matter 2006 6 The p+p Reference • Measurement at 200 GeV •nucl-ex/0610036 h p0 T => See poster by A. Bazilevsky! Baldo Sahlmüller Quark Matter 2006 7 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 Baldo Sahlmüller Quark Matter 2006 8 Au+Au at 200 GeV • h data from RHIC run 2004 => See poster by M.L. Purschke! Baldo Sahlmüller Quark Matter 2006 9 RAA at 200 GeV • h in Au+Au => Suppression by a factor of 5 in central events Baldo Sahlmüller Quark Matter 2006 10 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 Baldo Sahlmüller Quark Matter 2006 11 62.4 GeV Baldo Sahlmüller Quark Matter 2006 12 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 13 The p+p Reference • Problem: data sets inconsistent => large error new important RHIC measurement in 2006 Analysis still ongoing Baldo Sahlmüller Quark Matter 2006 14 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 Baldo Sahlmüller Quark Matter 2006 15 Spectra in Cu+Cu at 62.4 GeV h p0 => See poster by T. Sakaguchi! Baldo Sahlmüller Quark Matter 2006 16 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 Baldo Sahlmüller Quark Matter 2006 17 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 18 22.4 GeV Baldo Sahlmüller Quark Matter 2006 19 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 20 p0 at 22.4 GeV • Towards SPS energies: Cu+Cu at 22.4 GeV Little centrality dependence Baldo Sahlmüller Quark Matter 2006 21 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 22 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 Baldo Sahlmüller Quark Matter 2006 23 Particle Ratio Baldo Sahlmüller Quark Matter 2006 24 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 Baldo Sahlmüller Quark Matter 2006 25 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 Baldo Sahlmüller Quark Matter 2006 26 “World” data All PHENIX data consistent with world data Ratio shows no obvious energy dependence Baldo Sahlmüller Quark Matter 2006 27 Data vs. Theory? Baldo Sahlmüller Quark Matter 2006 28 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%) Baldo Sahlmüller Quark Matter 2006 29 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%) Baldo Sahlmüller Quark Matter 2006 30 Comparing to Theories and another compilation… Theory: William Horowitz 600 dNg 1600 dy (P robability 10%) Baldo Sahlmüller Quark Matter 2006 31 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 Baldo Sahlmüller Quark Matter 2006 32 Finally: Back to the List So far: status of investigating energy loss with high pT particle production; dependence on: – Centrality – pT – System size Baldo Sahlmüller OK OK (OK) Quark Matter 2006 33 Finally: Back to the List Now: status of investigating energy loss with high pT particle production; dependence on: – – – – Centrality pT System size Energy Baldo Sahlmüller OK OK OK OK Quark Matter 2006 34 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 Baldo Sahlmüller Quark Matter 2006 36