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STAR Results from RHIC Beam Energy Scan-I Lokesh Kumar (for STAR Collaboration) Outline:  Motivation  Accessing QCD Phase Diagram: T and  B  Searching.

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Presentation on theme: "STAR Results from RHIC Beam Energy Scan-I Lokesh Kumar (for STAR Collaboration) Outline:  Motivation  Accessing QCD Phase Diagram: T and  B  Searching."— Presentation transcript:

1 STAR Results from RHIC Beam Energy Scan-I Lokesh Kumar (for STAR Collaboration) Outline:  Motivation  Accessing QCD Phase Diagram: T and  B  Searching QCD Phase Boundary: Turning-off QGP signatures  Searching QCD critical point: Enhanced fluctuations  BES Phase-II  Summary Quark Matter 2012 August 12-18, 2012, Washington, DC Lokesh Kumar, QM20121

2 STAR BES Program: Motivation Main goals: Study the QCD phase diagram: - Search for the signals of possible phase boundary - Search for softening of EOS - Search for the possible QCD Critical Point 2 QCD Phase Diagram: arXiv: Important Steps: Proposal: Year 2008 Feasibility: Au+Au 9.2 GeV test run [STAR: PRC 81, (2010)] Year 2010: First phase started Year 2011: Two more energy points 2

3 Lokesh Kumar, QM2012 STAR Experiment 3 MRPC ToF Barrel BBC PMD EMC Barrel EMC End Cap TPC HLT FTPC Coverage: 0 <  < 2  |  | < 1.0 Uniform acceptance: All energies and particles Year√s NN (GeV) Events(10 6 ) *5Test Run Uncorrected N ch dN evt / (N evt dN ch ) BES-I Data: Rapidity p T (GeV/c) Au+Au 7.7 GeVAu+Au 200 GeV  p p 3

4 Lokesh Kumar, QM2012 Particle Identification 4 PID (TPC+TOF): pion/kaon: p T ~1.6 GeV/c proton p T ~3.0 GeV/c Strange hadrons: decay topology & invariant mass TPC TPC+TOF Au+Au 39 GeV 4

5 Lokesh Kumar, QM2012 Two Considerations 5 Changing energy in RHIC BES (higher to low √s NN ) and look at the energy dependence trend of various observables J. Randrup & J. Cleymans, Phys. Rev. C 74 (2006) RHIC BES Discuss the observations seen from the data at RHIC BES in view of above two possibilities  Encounter varying net-baryon density Change in baryon to meson ratio 1 st order phase transition effects  If lower energy only allows system to enter hadronic phase – Turn off of QGP signatures Two perspectives: In this talk: 5

6 Lokesh Kumar, QM2012 (A) Accessing Phase Diagram 6 T-  B : From spectra and ratios 6

7 Lokesh Kumar, QM2012 , K, p Spectra 7 STAR Preliminary Slopes:  > K > p Proton spectra: - without feed-down correction ,K,p yields within measured p T ranges: 70-80% of total yields 7

8 STAR Preliminary  Au+Au 39 GeV Lokesh Kumar, QM2012 Strange Hadron Spectra Au+Au 39 GeV K0sK0s  , K 0 s : Levy function fit  : Boltzmann fit  : feed-down corrected STAR Preliminary 8

9 Lokesh Kumar, QM2012 Freeze-out Parameters  Centrality dependence of freeze-out temperature with baryon chemical potential observed for first time at lower energies THERMUS Model: T ch and  B S. Das: Fri, 6B Particles used: , K, p, , K 0 s,  9 STAR Preliminary

10 Au+Au Lokesh Kumar, QM2012 Freeze-out Parameters  Higher kinetic temperature corresponds to lower value of average flow velocity and vice-versa Blast Wave: T kin and S. Das: Fri, 6B Particles used: ,K,p 10 STAR Preliminary

11 Lokesh Kumar, QM2012 (B) Turn-OFF of QGP Signals/Softening of Equation of State/1 st Order Phase Transition Au+Au 9.2 GeV AMPT: (GeV/c) v 1 vs. y: NCQ Scaling: R cp : Charge Separation: 1 st order phase tranisition? QGP? NCQ breaking in hadronic matter? Dense medium (QGP) L.P. Csernai et al., PLB 458, 454 (1999) F. Liu et al., JPG (2010) K. Fukushima et al., PRD 78, (2008) 11 Turn-off of QGP?

12 STAR Preliminary v1v1 Lokesh Kumar, QM2012 Directed Flow Mid-central collisions: Pion v 1 slope: Always negative ( GeV) (Net)-proton v 1 slope: changes sign between 7.7 and 11.5 GeV Y. Pandit: Tue, 1A 12

13 STAR Preliminary Lokesh Kumar, QM2012 Elliptic Flow  Difference in baryon-antibaryon v 2 increases with decreasing √s NN : S. Shi: Fri, 6B -- J. Dunlop et al., PRC 84, (2011) -- J. Xu et al., PRC 85, (2012) 13 Poster: A. Schmah #141  For anti-particles: Baryons and mesons show no splitting at 11.5 GeV   -meson v 2 deviates (~2  ) from others for √s NN ≤ 11.5 GeV: less collectivity contribution from partonic interactions baryon transport / hadronic interactions

14 STAR Preliminary Lokesh Kumar, QM2012 Dynamical Charge Correlations Splitting between same and opposite-sign charges: Decreases with decreasing √s NN and disappears below √s NN =11.5 GeV G. Wang: Thu, Plenary 14

15 STAR Preliminary Lokesh Kumar, QM2012 R cp Measurements  R CP (K 0 s ) 19.6 GeV  R CP > 1 for √s NN ≤ 11.5 GeV For p T > 2 GeV/c: X. Zhang: Thu, 5A E. Sangaline Thu, 5C 15 Poster: S. Horvat # 94 (Un)-Identified R cp :

16 Lokesh Kumar, QM2012 Phase Boundary Search With Nuclei Need higher statistics to make conclusive statement Y. Zhu: Thu, 5A 16 Strangeness Population Factor: Beam energy dependence of S 3 behaves differently in QGP and pure hadron gas - S. Zhang et al., PLB 684 (2010) J. Steinheimer et al.,PLB 714 (2012) 85

17 Lokesh Kumar, QM2012 (C) Searching QCD Critical Point √s observable Enhanced Fluctuations near Critical Point T. Andrews. Phil. Trans. Royal Soc., 159:575, 1869 CO 2 near liquid-gas transition Particle ratio fluctuations (2 nd moments) - K/ , p/ , K/p Conserved number fluctuations - Higher moments of net-protons, net-charge,.. 17

18 Lokesh Kumar, QM2012 Particle Ratio Fluctuations STAR observed monotonic behavior for particle ratio fluctuations vs. √s NN P. Tribedy: Tue, 2C 18 STAR Preliminary K/p STAR Preliminary p/  Poster: Z. Ahammed # 124

19 Lokesh Kumar, QM2012 Higher Moments: Net-protons  0-5% central collisions: Deviations below Poisson observed for √s NN > 7.7 GeV  Peripheral collisions: Deviations above Poisson observed for √s NN < 19.6 GeV  Higher statistics needed at 7.7 GeV and 11.5 GeV and possibly a new data point around ~15 GeV X. Luo: Fri, 7B         S  ~       19 Poster: Z. Li # 215

20 Lokesh Kumar, QM2012 Higher Moments: Net-charge         S  ~       STAR Preliminary  Data lies in between Poisson and HRG model expectations  Higher statistics needed at 7.7 GeV and 11.5 GeV and possibly a new data point around ~15 GeV D. McDonald: Fri, 7B 20 Posters: N. Sahoo # 557, A. Sarkar # 394

21 Lokesh Kumar, QM2012 Beam Energy Scan Phase- II 21

22 Lokesh Kumar, QM2012 BES Phase-II proposal  Electron cooling will provide increased luminosity ~ 10 times Proposal BES-II (Years ): A.Fedotov, W. Fischer, private discussions, √s NN (GeV)μ B (MeV) Requested Events(10 6 ) Au+Au Au+Au Au+Au Au+Au U+U: ~20~ % Au target - Annular 1% gold target inside the STAR beam pipe - 2m away from the center of STAR - Data taking concurrently with collider mode at beginning of each fill : No disturbance to normal RHIC running Fixed Target Proposal: Poster: B. Haag #

23 Lokesh Kumar, QM2012 STAR BES Program Summary √s NN (GeV)  B (MeV) QGP properties BES phase-I Test Run Fixed Target BES phase-II Large range of  B in the phase diagram !!! Explore QCD Diagram 23

24 Lokesh Kumar, QM2012 Summary  Phase Diagram: - Large  B range covered by the STAR in the phase diagram - Centrality dependence of T ch vs.  B observed for the lower energies  Phase Boundary: - Proton v 1 slope changes sign between 7.7 GeV and 11.5 GeV - Particles-antiparticles v 2 difference increases with decreasing √s NN -  -meson v 2 deviates from others for √s NN ≤ 11.5 GeV - Dynamical charge correlations: vanish below 11.5 GeV - R cp > 1 for p T > 2 GeV/c and √s NN ≤ 11.5 GeV  Critical Point: - Ratio fluctuations (2 nd moment) show monotonic behavior vs. √s NN - Deviation from Poisson observed for higher moments of net-protons  BES-II: - Propose higher statistics data below 20 GeV - Fixed target proposal to extend  B coverage up to 800 MeV 24

25 Thanks Thanks to STAR Collaboration Argonne National Laboratory, Argonne, Illinois Brookhaven National Laboratory, Upton, New York University of California, Berkeley, California University of California, Davis, California University of California, Los Angeles, California Universidade Estadual de Campinas, Sao Paulo, Brazil University of Illinois at Chicago, Chicago, Illinois Creighton University, Omaha, Nebraska Czech Technical University in Prague, FNSPE, Prague, , Czech Republic Nuclear Physics Institute AS CR, \v{R}e\v{z}/Prague, Czech Republic University of Frankfurt, Frankfurt, Germany Institute of Physics, Bhubaneswar , India Indian Institute of Technology, Mumbai, India Indiana University, Bloomington, Indiana Alikhanov Institute for Theoretical and Experimental Physics, Moscow, Russia University of Jammu, Jammu , India Joint Institute for Nuclear Research, Dubna, , Russia Kent State University, Kent, Ohio University of Kentucky, Lexington, Kentucky, Institute of Modern Physics, Lanzhou, China Lawrence Berkeley National Laboratory, Berkeley, California Massachusetts Institute of Technology, Cambridge, MA Max-Planck-Institut f\"ur Physik, Munich, Germany Michigan State University, East Lansing, Michigan Moscow Engineering Physics Institute, Moscow Russia NIKHEF and Utrecht University, Amsterdam, The Netherlands Ohio State University, Columbus, Ohio Old Dominion University, Norfolk, VA, Panjab University, Chandigarh , India Pennsylvania State University, University Park, Pennsylvania Institute of High Energy Physics, Protvino, Russia Purdue University, West Lafayette, Indiana Pusan National University, Pusan, Republic of Korea University of Rajasthan, Jaipur , India Rice University, Houston, Texas Universidade de Sao Paulo, Sao Paulo, Brazil University of Science \& Technology of China, Hefei , China Shandong University, Jinan, Shandong , China Shanghai Institute of Applied Physics, Shanghai , China SUBATECH, Nantes, France Texas A\&M University, College Station, Texas University of Texas, Austin, Texas University of Houston, Houston, TX, Tsinghua University, Beijing , China United States Naval Academy, Annapolis, MD Valparaiso University, Valparaiso, Indiana Variable Energy Cyclotron Centre, Kolkata , India Warsaw University of Technology, Warsaw, Poland University of Washington, Seattle, Washington Wayne State University, Detroit, Michigan Institute of Particle Physics, CCNU (HZNU), Wuhan , China Yale University, New Haven, Connecticut University of Zagreb, Zagreb, HR-10002, Croatia Thank You Lokesh Kumar, QM201225

26 BES Related Talks at QM2012 1). Beam Energy Dependence of Strange Hadron Production at RHIC: Xiaoping Zhang, Thu-5A, 15:00 2). Beam Energy Dependence of Hypertriton Production and Lifetime Measurement: Yuhui Zhu, Thu-5A:15:40 3). Centrality dependence of freeze-out parameters from the Beam Energy Scan at STAR: Sabita Das, Fri-6B:15:00 4). Di-electron production dependence on transverse momenta, reaction plane, centralities and collision energies in Au+Au collisions at STAR: Bingchu Huang, Wed-3C: 09:10 5). $R_{CP}$ and $R_{AA}$ Measurements of Identified and Unidentified Charged Particles at High $p_{T}$ in Au+Au Collisions at $\sqrt{s_{NN}}=$7.7, 11.5, 19.6, 27, 39, and 62.4 GeV in STAR: Evan Sangaline, Thu-5C: 15:00 6). Event anisotropy $v_2$ of charged and identified particles in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 19.6, 27, 39 and 62.4 GeV with STAR: Shusu Shi, Fri-6B: 15:20 7). Study of Net-proton High Order Cumulant in STAR at RHIC: Lizhu Chen, Tue-2C: 15:40 8). Search for the QCD Critical Point by Higher Moments of Net-proton Multiplicity Distributions at STAR: Xiaofeng Luo, Fri-7B: 17:30 9). Beam energy and centrality dependence of the statistical moments of the net-charge, net-kaon and total pion multiplicity distributions in Au+Au collisions at STAR: Daniel McDonald, Fri-7B: 16:50 10). Beam Energy Dependence of First and Higher-Order Flow Harmonics from the STAR Experiment at RHIC: Yadav Pandit, Tue-1A: 14:55 11). Search for QCD Phase Transitions and the Critical Point Utilizing Particle Ratio Fluctuations and Transverse Momentum Correlations from the STAR Experiment: Prithwish Tribedy, Tue-2C: 16:45 12). Search for the Chiral Magnetic Effects in High-Energy Nuclear Collisions: Gang Wang, Thu-IVB: 12:20 13). Femptoscopy of identified particles at STAR: Neha Shah, Tue-1C: 14:35 Lokesh Kumar, QM201226

27 BES Related Posters at QM2012 Lokesh Kumar, QM Poster #PresenterTitle 215 Zhiming Li Dynamical higher cumulant ratios of net and total protons at STAR 269 Bingchu Huang Low mass di-electron production in Au+Au collisions at $\sqrt{s_{_{NN}}} = 19.6$ GeV at STAR 385 Brook Haag Results from Fixed-Target Collisions at RHIC: Au+Al at $\root{S_{NN}}$ = 4.5, 3.5 and 3.0 GeV 113 Patrick Huck Dielectron Production in Au+Au-Collisions at $\sqrt{s_{NN}}$ =39 \& 62.4 GeV at STAR 94 Stephen Horvat Collision energy dependence of high transverse momentum $R_{CP}$ of charged hadrons in STAR 557 Nihar Sahoo Higher moments of net-charge multiplicity distributions at RHIC energies from STAR 308 Bill Llope Light (anti)nucleus production in $\sqrt{\rm s_{\rm NN}}$$=$ GeV Au$+$Au collisions in the STAR Experiment 124 Zubayer Ahmed Measurement of energy dependence of K/pi fluctuation in STAR experiment at RHIC 394 Amal Sarkar Higher moments of Net Kaon multiplicity distributions at RHIC energies for the search of QCD Critical Point

28 BES Related Posters at QM2012 Lokesh Kumar, QM Poster #PresenterTitle 263 John Novak Incident Energy Dependence of Transverse Momentum Correlations in Au+Au collisions at sqrt(sNN) = GeV in STAR 141 Alexander Schmah Observation of a difference in v2 between particles and anti-particles in Au+Au collisions at $\sqrt{s_{NN}}$ = GeV with STAR 121 Hui Wang Beam energy dependent charge balance functions in heavy ion collisions at STAR

29 Lokesh Kumar, QM2012 Back up 29

30 Lokesh Kumar, QM2012 Chemical Freeze-out Statistical-Thermal Model (THERMUS):  Fitted particle ratios with THERMUS  Used grand-canonical approach  Two main parameters: T ch and  B  =1/T; -1(+1) for fermions (bosons), Z=partition function; m i = mass of hadron species i; V = volume; T = Temperature; K 2 = 2 nd order Bessel function; g i = degeneracy;  i = chemical potential 30

31 Lokesh Kumar, QM2012 Chemical Freeze-out 31

32 Lokesh Kumar, QM2012 Elliptic Flow Rate of increase of v 2 is slow from GeV 32

33 Lokesh Kumar, QM2012 Baryon-Meson Ratio 33 STAR Preliminary

34 Lokesh Kumar, QM2012 C 6 /C 2 34 L. Chen: Tue, 2C

35 Lokesh Kumar, QM2012 Fixed Target Set-up 35


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