Nu Xu1/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Results from RHIC Beam Energy Scan-I Nu Xu (1,2) Outline: 1) Introduction 2) Selected Results from RHIC BES-I 3) Remarks on Observables in CBM (1) College of Physical Science & Technology, Central China Normal University, China (2) Nuclear Science Division, Lawrence Berkeley National Laboratory, USA

Nu Xu2/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 STAR Physics Focus Polarized p+p Program - proton intrinsic properties Small-x Physics Program - Low-x properties, initial condition, CGC - Elastic and inelastic processes in pp2pp 1) At 200 GeV at RHIC - Deconfinement* & medium properties, EoS - pQCD in hot and dense medium 2) RHIC Beam Energy Scan (BES-I) - QCD phase structure*: phase boundary & critical point - Chiral symmetry restoration* STAR Decadal Plan eRHIC (eSTAR) STAR Decadal Plan eRHIC (eSTAR) * Holy Grail for the physics of high-energy nuclear collisions

Nu Xu3/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 STAR Experiment STAR Collaboration

Nu Xu4/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 STAR Detector Configurations  STAR: Large coverage, excellent PID, fast DAQ - detects nearly all particles produced at RHIC - multiple fold correlation measurements - Probes: bulk, penetrating, and bulk-penetrating  STAR: Perfect Mid-y Collider Experiment PeriodDetectorsPhysics TPCu, d, s 2010TPC + TOFu, d, s + dilepton 2013TPC + TOF + MTD* u, d, s, c, b + dilepton 2014TPC + TOF + MTD+HFT

Nu Xu5/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Particle Identification at STAR TPC TOF EMC HFT Neutral particles e, μ π K p d TPC TOF TPC Log 10 (p) Multiple-fold correlations from identified particles! Hyperons & Hyper-nuclei Jets Heavy-flavor hadrons MTD High p T muonsJets & Correlations Charged hadrons

Nu Xu6/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Beam Energy Scan at RHIC Observations: (1) Azimuthally HBT 1st order phase transition (2) Directed flow v 1 1st order phase transition (3) Dynamical correlations partonic vs. hadronic dof (4) v 2 - NCQ scaling partonic vs. hadronic dof (5) Fluctuations Critical point, correl. length - /public/sn arXiv: Study QCD Phase Structure - Signals of phase boundary - Signals for critical point

Nu Xu7/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Bulk Properties at Freeze-out Kinetic Freeze-out: - Central collisions => lower value of T kin and larger collectivity β - Stronger collectivity at higher energy Chemical Freeze-out: (GCE) - Central collisions => higher values of T ch and μ B ! - The effect is stronger at lower energy. STAR: S. Das, L. Kumar QM2012

Nu Xu8/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Di-electrons: √s NN Dependence Chiral symmetry (restoration?) and direct radiations: 1)LMR enhancement vs. collision energy, mass cut dependence 2)Future Heavy Flavor Tracker and Muon Telescope Detector upgrades: - correlated charm contributions - extract direct radiation information STAR: B.C. Huang, P. Huck, QM2012

Nu Xu9/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 y x pypy pxpx coordinate-space-anisotropy  momentum-space-anisotropy Anisotropy Parameter v 2 Initial/final conditions, EoS, degrees of freedom

Nu Xu10/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Low p T (≤ 2 GeV/c): hydrodynamic mass ordering High p T (> 2 GeV/c): number of quarks scaling  Partonic Collectivity, necessary for QGP!  De-confinement in Au+Au collisions at RHIC! Partonic Collectivity at RHIC STAR: preliminary QM09: arXiv

Nu Xu11/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 NCQ Scaling in v 2 - m  ~ m p ~ 1 GeV - ss  φ not K + K -  φ -   h <<  p ,  In the hadronic case, no number of quark scaling and the value of v 2 of φ will be small. * Thermalization is assumed!  

Nu Xu12/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Collectivity v 2 Measurements 1)Systematic measurements of collectivities 2)At lower beam energies, the number of quark scaling is broken. Hadronic interactions become dominant, especially for √s NN < 11.5 GeV STAR Preliminary STAR: Nasim Md, S.S. Shi, QM2012 STAR: Nasim Md, S.S. Shi, QM2012

Nu Xu13/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 NCQ Scaling of v 2 /v 3 & J/ψ R AA PHENIX: E. O’Brien, QM2012 √s NN ≥ 39 GeV, measured v i (i=2,3) and J/ψ R AA show no energy dependence  Partonic interaction and sQGP dominant for collisions at √s NN ≥ 39 GeV

Nu Xu14/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Search for Local Parity Violation in High Energy Nuclear Collisions The separation between the same-charge and opposite- charge correlations. - Strong external EM field - De-confinement and Chiral symmetry restoration L or B AAA AA 1)Parity-even observable, assumptions must be tested 2)Energy dependence & UU collisions - S. Voloshin, PRC62, (00). - STAR: PR103, ; PRC81, (2009)

Nu Xu15/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Dynamical Correlations vs. √s NN (1)Below √s NN = 11.5 GeV, the splitting between the same- and opposite-sign charge pairs (SS-OS) disappear (2)If QGP is the source for the observed splitting at high-energy nuclear collisions  hadronic interactions become dominant at √s NN ≤ 11.5 GeV STAR Preliminary SS - OS STAR: G. Wang, QM2012

Nu Xu16/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 √s NN = 193GeV U+U Collisions body-body tip-tip U+U Collisions: (1) test CME with small external B-field (2) test v 2 at 30% higher density (3) test path-length dependence of R AA 1)Comparing to Au+Au collisions, v 2 values are higher in U+U 2)At 1% most central collisions, v 2 is found to be finite & SS-OS=0! STAR: G. Wang, QM2012

Nu Xu17/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Higher Moments 1) High moments for conserved quantum numbers: Q, S, B, in high-energy nuclear collisions 2)Sensitive to critical point (ξ correlation length): 3)Direct comparison with Lattice results: 4)Extract susceptibilities and freeze-out temperature. An independent/important test on thermal equilibrium in heavy ion collisions. - A. Bazavov et al (NLOTE) - R.V. Gavai and S. Gupta, PLB696, 459(2011) - S. Gupta, et al., Science, 332, 1525(2011) - STAR Experiment: PRL105, 22303(2010) - M. Stephanov: PRL102, (2009) - F. Karsch et al, PLB695, 136(2011) - M.Cheng et al, PRD79, (2009) - Y. Hatta, et al, PRL91, (2003)

Nu Xu18/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Higher Moment: Net-charge STAR Preliminary 1)Preliminary net-charge results: efficiency, decay, … effects under study 1)Higher statistics data needed below 20 GeV - HRG Model: K. Redlich et al, private communications STAR: D. McDonald, QM2012

Nu Xu19/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 RHIC BES-I RHIC BES-I STAR net-proton results: 1)All data show deviations below Poisson beyond statistical and systematic errors in the 0-5% most central collisions for κσ 2 and Sσ at all energies. Larger deviation at √s NN ~ 20GeV 2)UrQMD model show monotonic behavior 3)Higher statistics needed for collisions at √s NN < 20 GeV Net-proton Higher Moments BES-II STAR Preliminary STAR: X.F. Luo, QM2012

Nu Xu20/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 e-cooling at RHIC for BES-II Fermi Lab Pelletron A. Fedotov, W. Fischer, private discussions, √s NN (GeV)~ 5~ 20 Increasing factor* Requested to install the e-cooling device - BES-II data taking in

Freeze-out E T /N ch RHIC Beam Energy Scan-I √s NN (GeV)μ B* (MeV)Events(10 6 ) * for central collisions Directed Flow v 1 Elliptic Flow v 2 Strangeness Jet Quenching Higher Moments Changes at √s NN < 20 GeV, calls for higher statistics data!

Nu Xu22/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, T E RHIC, SPS, FAIR 3 3 Phase boundary RHIC, FAIR, NICA Exploring the QCD Phase Structure 1 1 T ini, T C LHC, RHIC 2 Partonic Matter Hadronic Matter μ B (MeV) RHIC Top Energy Study QGP Properties - heavy flavor hadrons - di-leptons - Jets RHIC Top Energy Study QGP Properties - heavy flavor hadrons - di-leptons - Jets BES-II Map the QCD Phase Structure HI collisions at √s NN ≤ 20 GeV BES-II Map the QCD Phase Structure HI collisions at √s NN ≤ 20 GeV

Nu Xu23/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Summary 1) BES-I Program: - Partonic QGP dominant: √s NN > 39 GeV Hadronic interactions become dominant: √s NN ≤ 11.5 GeV - High statistics data for energy region √s NN ≤ 20 GeV, needs e-cooling at RHIC => BES-II 2) Jets, Heavy Flavor and Di-lepton Programs: PHENXI: sPHENIX, full jets reconstruction, ready by 2018 STAR: HFT+MTD upgrades, ready by summer of 2014 In the coming decade, RHIC provides unique opportunities for exploring matter with QCD degrees of freedom!

Nu Xu24/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, T E RHIC, SPS, FAIR 3 3 Phase boundary RHIC, FAIR, NICA Key Observables for CBM 1 1 T ini, T C LHC, RHIC 2 Partonic Matter Hadronic Matter μ B (MeV) SIS300 + IS A MUST! (√s NN ~ GeV, μ B ~ GeV) Region of extreme baryon density! CBM Key Observables 1) Strangeness production: * phases of the matter, EOS, FO 2) Correlation/fluctuation, light nuclei: * critical point, local-phase-space-density 3) Di-leptons: * space-time-evolution of the matter * Chiral symmetry related properties SIS300 + IS A MUST! (√s NN ~ GeV, μ B ~ GeV) Region of extreme baryon density! CBM Key Observables 1) Strangeness production: * phases of the matter, EOS, FO 2) Correlation/fluctuation, light nuclei: * critical point, local-phase-space-density 3) Di-leptons: * space-time-evolution of the matter * Chiral symmetry related properties

Nu Xu25/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Acknowledgements:  STAR Collaboration  Higher Moments: S. Gupta, F. Karsch, V. Koch, X.F. Luo, L. McLerran, B. Mohanty, K. Rajagopal, K. Redlich, M. Stephanov, H.G. Ritter  Freeze-out & Collectivity: P. Braun-Munzinger, S. Das, U. Heinz, M. Kaneta, D. Keane, L. Kumar, F. Liu, B. Mohanty, H.G. Ritter, A. Schumah, S.S. Shi, S. Voloshin, F.Q. Wang, X.P. Zhang  Strangeness: H.Z. Huang, B. Mohanty, E. Shuryak  Di-lepton & Heavy Flavor: P. Braun-Munzinger, X. Dong, V. Koch, Y.P. Liu, R. Rapp, K. Schweda, J. Stroth, Y.F. Zhang, J. Zhao, P.F. Zhuang

Nu Xu26/26 ”The 20 th CBM Collaboration Meeting“, Kolkata, India, September 24 – 28, 2012 Net-proton Higher Moments 1)Higher sensitivity expected from higher order moments 2)STAR first net-proton C 6 /C 2 results, wide centrality bins 1)More data needed especially for collisions below 20 GeV - B. Friman, F. Karsch, K. Redlich, V. Skokov, Eur. Phys. J. C (2011). - STAR: L.Z. Chen, QM2012 STAR Preliminary STAR: L.Z. Chen, QM2012