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NQ-scaling for Phase Boundary F. Liu (1) , K.J. Wu (1) , and N. Xu (2)

NQ-scaling for Phase Boundary F. Liu (1) , K.J. Wu (1) , and N. Xu (2) (1) Institute of Particle Physics, China Center Normal University, Wuhan, China (2) Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, 94720 CA, USA Many Thanks to the Organizers!. Outline.

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NQ-scaling for Phase Boundary F. Liu (1) , K.J. Wu (1) , and N. Xu (2)

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  1. NQ-scaling for Phase Boundary F. Liu(1), K.J. Wu(1), and N. Xu(2) (1) Institute of Particle Physics, China Center Normal University, Wuhan, China (2) Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, 94720 CA, USA Many Thanks to the Organizers!

  2. Outline • Introduction • Recent v2 results from RHIC • A proposal: using NQ scaling in v2 for locating the possible QCD phase boundary • Summary

  3. Elliptic Flow (v2) hadronic partonic Coordinate-Space Anisotropy Momentum-Space Anisotropy interactions • Strange hadron: less sensitive to late hadronic rescattering • Elliptic flow => • Early stage collision dynamics • Good probe of the early stage of the collision , Ω, Ξ, Λ D , K, p

  4. 200 GeV: Centrality Dependence STAR: Phys. Rev. C77, 54901(2008) 200 GeV Au+Au S. Voloshin, A. Poskanzer, PL B474, 27(00). D. Teaney, et. al., nucl-th/0110037 • Larger v2/part indicates stronger flow in more central collisions. • NO partscaling. • The observed nq-scaling does not necessarily mean thermalization.

  5. System Size Driven Collectivity STAR Preliminary Collectivity: Driven by number of participants, NOT by eccentricity. Caution: Local equilibrium andPerfect fluid

  6. φ-meson Flow: Partonic Flow STAR: Phys. Rev. Lett. 99, 112301(2007). “φ-mesons (and other hadrons) are produced via coalescence of seemingly thermalized quarks in central Au+Au collisions. This observation implies hot and dense matter with partonic collectivity has been formed at RHIC” STAR: Phys. Rev. Lett. 99, 112301(2007)

  7. Partonic Collectivity at RHIC STAR: preliminary STAR: QM2009 0907.2265 Low pT(≤ 2 GeV/c): hydrodynamic mass ordering High pT (> 2 GeV/c): number of quarks ordering s-quark hadron: smaller interaction strength in hadronic medium light- and s-quark hadrons: similar v2 pattern => Collectivity developed at partonic stage!

  8. Collectivity, De-confinement at RHIC - v2 of light hadrons and multi-strange hadrons - scaling by the number of quarks At RHIC: nq-scaling novel hadronization process • Partonic flow • De-confinement • PHENIX: PRL91, 182301(03) • STAR: PRL92, 052302(04), 95, 122301(05) • nucl-ex/0405022, QM05 • S. Voloshin, NPA715, 379(03) • Models: Greco et al, PRC68, 034904(03) • Chen, Ko, nucl-th/0602025 • Nonaka et al. PLB583, 73(04) • X. Dong, et al., Phys. Lett. B597, 328(04). • …. i ii

  9. The QCD Critical Point - LGT prediction on the transition temperature TC is robust. - LGT calculation, universality, and models hinted the existence of the critical point on the QCD phase diagram* at finite baryon chemical potential. - Experimental evidence for either the critical point or 1st order transition is important for our knowledge of the QCD phase diagram*. * Thermalization has been assumed M. Stephanov, K. Rajagopal, and E. Shuryak, PRL 81, 4816(98); K. Rajagopal, PR D61, 105017 (00) http://www.er.doe.gov/np/nsac/docs/Nuclear-Science.Low-Res.pdf RHIC (200) & LHC: Determine the temperature Tini, TC BES: Explore the QCD phase diagram TE and the location phase boundary

  10. STAR experience with Low Energy RHIC running observed apparent rates of collisions surprisingly high (?!) to do: (1) understand background (2) optimize triggering 2001: 19.6 GeV Au+Au 2004: 22.4 GeV Cu+Cu 2007: 9 GeV Au+Au Collectivity from STAR at 9.2GeV STAR TPC image of 9 GeV Au+Au, taken on June 7, 2007 (run 8158119, ev.44), figure from Jeff Langraf

  11. STAR Experiment and Collisions at Ecm= 9.2 GeV Collisions recorded in STAR TPC Excellent Particle Identification Analysis based on ~ 3000 good events collected at ~ 0.7 Hz in year 2008 PID will further strengthen with the completion of ToF

  12. Azimuthal Anisotropy - Elliptic Flow QM08 Lokesh Kumar for STAR With TOF, the pt region will be extended to a higher value. Important to perform the v2 scaling analysis.

  13. RHIC run 10 (fall 2009) (1) Large energy range accessible (2) Collider geometry (acceptance won’t change with S, track density varies slowly) (3) STAR detectors well suited (large acceptance), tested & understood STAR PAC 2007 Strawman proposal: Note: NA61 @ CERN (starting in 2010): 10, 20, 30, 40, 80, 158 GeV/c

  14. Au+Au Collisions at 9.2 GeV AMPT (v2.1) J. Tianet al, Phys. Rev. C79, 067901(2009).

  15. Au+Au Collisions at 9.2 GeV AMPT (v2.1) • AMPT model results: • In AMPT, the scaling in v2 is independent of partonic cross sections • The amplitude of v2 depends on the value of the cross section • => • The beam energy dependence of the partonic cross sections will not affect the v2 scaling argument. Important for BES program. σp = 3mb σp = 10mb

  16. RQMD and uRQMD Results • These hadronic models predicted a lower v2(pT) compare to that from AMPT hadronic mode calculations. • They also show a scaling better than that from AMPT hadronic mode calculations, due to the number of quark scaling in hadron cross sections used. • Multi-strange hadrons, φ and Ω, for example, are important for a clean measurement.

  17. Observable*: Quark Scaling in v2  • m ~ mp ~ 1 GeV • ssφnot K+K-φ • h<<p,  • In the hadronic case, no number • of quark scaling and the value of • v2ofφ will be small. • * Thermalization is assumed!

  18. Energy Dependence of the v2-scaling and the QCD Phase Boundary • Summary • NQ scaling in v2: partonic collectivity&de-confinement in high-energy nuclear collisions. • Scaling in v2: partonic dofdominants • No scaling in v2: hadronic dofdominants • The multi-strange hadrons are particularly clean for the search, φ, for example. • Together with other observables: • Fluctuations, Kurtosis, LPV, clusters … • F. Liu(1), K.J. Wu(1), and N. Xu(2) • (1) Institute of Particle Physics, China Center Normal University, Wuhan, China • (2) Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, 94720 CA, USA

  19. Tests withφ-mesons in uRQMD • φ-mesons from string show weak collectivity &does not follow the nq-scaling. • Coalescence φ-mesons from K+K- (/4) fit the nq-scaling in pT<= 2 GeV/c region. (/4)

  20. Anisotropy Parameter v2 coordinate-space-anisotropy  momentum-space-anisotropy y py px x Initial/final conditions, EoS, degrees of freedom

  21. MC vs. AuAu@9.2GeV Data Lokesh Kumar QM2009, SQM2008 Only 3k good events for the experimental data. v2 : AMPT with melting > AMPT default > UrQMD >RQMD. Partonic reactions enhance hadrons v2 !

  22. The QCD Phase Diagram and High-Energy Nuclear Collisions Ti, TC LHC, RHIC TE RHIC, FAIR Phase Boundary RHIC,FAIR, NICA 3 2 1 quark-gluon plasma Early Universe 1 2 3 Tc Critical Point? • Temperature hadron gas CSC nuclei • Baryon Chemical Potential

  23. MC vs. Experimental data Only 3k good events for experimental data. Difficult to say which MC model is best suitable.

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