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Zhangbu Xu (Brookhaven National Lab)

Free Quarks Constituent Quark Scaling of Flow Heavy Quark Thermalization Color Screening of Heavy Quarkonia Excited Vacuum Novel symmetries in QCD Dileptons as tool to systematically study Chiral Symmetry Restoration (Super-)Statistical Fluctuation in particle production

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Zhangbu Xu (Brookhaven National Lab)

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  1. Free Quarks • Constituent Quark Scaling of Flow • Heavy Quark Thermalization • Color Screening of Heavy Quarkonia • Excited Vacuum • Novel symmetries in QCD • Dileptons as tool to systematically study Chiral Symmetry Restoration • (Super-)Statistical Fluctuation in particle production • Initial state of gluonic matter in nuclear collisions • Search for Critical Point Recent RHIC Heavy-Ion Results Zhangbu Xu (Brookhaven National Lab)

  2. STAR Preliminary

  3. Free Quarks Excited Vacuum Quark Matter 1995

  4. NCQ Scaling STAR, arXiv:0909.0566 [nucl-ex] PHENIX, PRL 99, 052301 (2007) d(p+n) : nq = 2 x 3 3He(2p+n) : nq = 3 x 3 • Number of constituent quark scaling holds well for v2 of 3He.

  5. Sakaguchi, S.L. Huang, QM2012 Beam Energy and Species S.S. Shi, QM2012 • Many measurements show impressive scaling • Many others show deviations: • PID v2 by ALICE • U+U 0-2% PID v2 by PHENIX • Different pt ranges and centralities

  6. Flow of Heavy Quarks Elliptic flow of Electrons from heavy-flavor hadrons Different flow methods: large flow at low pt Jet contribution at high pt Dong, Wei, Tlusty QM2012 First measurement of directly reconstructed Charmed hadron radial flow at RHIC

  7. Integrated J/ yield ALICE: Arnaldi, Arsene, Safarik, Scomparin PHENIX: PRC84(2001)054912 • Npart dependence of J/ RAA: • less suppression at LHC compared to at RHIC in central collisions • interplay between CNM, color screening and ccbar recombination • consistent with more significant contribution from ccbar recombination at LHC energies

  8. J/pT dependence in A+A PHENIX: PRL98(2007)232301 STAR: arXiv: 1208.2736, Trzeciak, Xie CMS: Mironov, Moon, Roland ALICE: Arnaldi, Safarik, Scomparin, Yang • J/ RAA decreases from low to high pTat LHC. • J/ RAA increases from low to high pTat RHIC. • At high pT, J/ more suppressed at LHC. • Models incorporating color screening andrecombinationcan consistently • describe the J/suppression pattern and flow measurements.

  9. Suppression without flow RHIC: large suppression, zero flow LHC: less suppression, hints of flow Color Screening and quark coalescence STAR Preliminary

  10. Suppressionin A+A STAR: Dong, Trzeciak, Xie (QM2012) CMS: arXiv: 1208.2826, Mironov, Rangel, Roland (1s) suppression magnitude consistent with excited states suppression. (2S) strongly suppressed, (3S) completely melted. Last piece of convincing evidence: color screening features of hot, dense medium in light of RHIC and LHC precise quarkonium measurements.

  11. Novel Symmetries STAR, PRL 103, 251601 Local Parity Violation Chiral Symmetry • Crucial to verify if parity violation is the correct explanation • U+U collisions: collisions with more v2 and less B field than Au+Au

  12. ALICE, arXiv:1207.0900 Beam energy scan From 2.76 TeV to 7.7 GeV, changes start to show from the peripheral collisions. (Wang, QM2012)

  13. The difference between OS and SS is still there in U+U, with similar magnitudes. • Consider OS-SS to be the signal Chiral Magneticin U+U 20-40% STAR Preliminary (Wang, QM2012) • A dedicated trigger selected events with 0-1% spectator neutrons. • With the magnetic field suppressed, the charge separation signal disappears (while v2 is still ~ 2.5%). 70-80% 0-5%

  14. Electric Quadrupole Y. Burnier, D. E. Kharzeev, J. Liao and H-U Yee, Phys. Rev. Lett. 107, 052303 (2011) Chiral Magnetic Wave Wang, QM2012

  15. Energy dependence of di-electron spectra 20-40% STAR: Dong, Geurts, Huang, Huck PHENIX: Atomssa, Tserruya PHENIX HBD results at 200 GeV : consistent with previous publication in 20-92% centrality. STAR results: systematically study the di-electron continuum from 19.6, 39, 62.4and 200GeV. Observe enhancement above cocktails in low mass range (~0.5 GeV/c2)

  16. Direct photon spectra and elliptic flow • Low pT direct photon elliptic flow measurement could provide direct constraints on QGP dynamics (η/s, T, t0…). • Excess of direct photon yield over p+p: Teff=221 ± 19 ± 19 MeV in 0-20% Au+Au; substantial positive v2 observed at pT<4 GeV/c. • Di-lepton v2 versus pT & Mll: probe the properties of the medium from hadron-gas dominated to QGP dominated. (R. Chatterjee, D. K. Srivastava, U. Heinz, C. Gale, PRC75(2007)054909) PHENIX, arXiv: 1105.4126 PHENIX: PRL104 (2010)132301 pT (GeV/c) Ruan, QM2012

  17. Di-electron v2 at 200 GeVAu+Au • Cocktail simulation is consistent with the • measured di-electron v2 at Mee<1.1 GeV/c2. • Need a factor of two more data to be sensitive • to hardon gas and QGP contribution, in • addition to independent measurements to • disentangle ccbar correlation contribution R. Chatterjee, D. K.Srivastava, U. Heinz, C. Gale, PRC75(2007)054909) STAR: Cui, Geurts, Huang QM2012

  18. Quantify the Enhancements Temperature dependence of rho spectral function Beam energy range where final state is similar Initial state and temperature evolution different Density dependence by Azimuthal dependence (v2) Use centrality dependence as another knob

  19. A tool to study Chiral Symmetry Restoration Ruan, QM2012 NA60, Eur.Phys.J.C59(2009)607 STAR: Cui, Dong, Geurts, Huang, Huck CERES: Eur.Phys.J.C41(2005)475

  20. Pillars of Discoveries in QGP physics Horowitz,1104.4958

  21. Cold QCD matter – the initial state at RHIC RHIC may provide unique access to the onset of saturation 2000—2008: yields 2008—: mono-jet 2009—: statistics/fluctuation STAR preliminary peripheral dAu central dAu pp PHENIX, PRL107

  22. Counting (Glittering) Tribedy, Venugopalan PLB710 Gelis, Lappi, McLerran, NPA 828 (2009) PHENIX PRC 78

  23. Where is the QCD critical point? • A landmark on the QCD phase diagram

  24. Thermodynamic properties of hot QCD state A thermodynamic state is specified by a set of values of all the thermodynamic parameters necessary for the description of the system. --- statistical mechanics by K. Huang Temperature (T), chemical potential (m), pressure(P), viscosity () … • Chemical/thermal Equilibrium at certain stage of the evolution • At the predicted QCD phase boundary • persistent from SPS to RHIC • Temperature decreases at AGS and SIS A. Andronic et al., NPA 837 (2010) 65

  25. Predictable Production Rate Why is it so predictable? T=164MeV? + - A. Andronic, P. Braun-Munzinger, J. Stachel, and H. Stocker, Phys.Lett.B697:203-207,2011

  26. Directed Flow of Protons • Directed flow (v1) slope: • sensitive to 1st order phase transition. • Proton v1 slope changes sign from + to – between 7.7 and 11.5 GeV and remains small but negative up to 200 GeV. • v1 slopes for other particles are all negative. • “net-proton” v1 slope shows a minimum around 11.5-19.6 GeV. • AMPT/UrQMD models cannot explain data. Pandit, Dong (STAR), QM2012 (GeV)

  27. Higher Moments of Net-protons Net-proton/Net-charge/Net-kaon X.F. Luo, L.Z. Chen for STAR, QM2012

  28. Negative Binomials fit all data Net charge Net kaon

  29. Negative-Binomial Distribution vs. Tsallis Tsallis entropy: generating function: average and variance: Non extensivity: k =  Poisson distribution “Partition function”: k = - N binomial distribution Aguiar, Kodama, PA320, 2003

  30. Spectra by same statistics Are Heavy-Ion collisions governed by a set of generic statistic rules, which also exist in other complex systems? What does this physics tell us about statistics in complex systems. How do we use the existing tools to extract information beyond “normal” statistics?

  31. Aims and scope To bring together scientists who have made contributions to Tsallis entropy and those who study complex systems. In physics, the Tsallis entropy is a generalization of the standard Boltzmann-Gibbs entropy. It was introduced in 1988 by ConstantinoTsallis as a basis for generalizing the standard statistical mechanics. In the scientific literature, the physical relevance of the Tsallis entropy was occasionally debated. However, from the years 2000 on, an increasingly wide spectrum of natural, artificial and social complex systems have been identified which confirm the predictions and consequences that are derived from this nonadditive entropy, such as nonextensive statistical mechanics, which generalizes the Boltzmann-Gibbs theory. Among the various experimental verifications and applications presently available in the literature, the following ones deserve a special mention: - The distribution characterizing the motion of cold atoms in dissipative optical lattices, predicted in 2003 and observed in 2006. - The fluctuations of the magnetic field in the solar wind enabled the calculation of the q-triplet (or Tsallis triplet) . - Spin glass relaxation. - Trapped ion interacting with a classical buffer gas. - High energy collisional experiments at LHC/CERN (CMS, ATLAS and ALICE detectors) and RHIC/Brookhaven (STAR and PHENIX detectors). Among the various available theoretical results which clarify the physical conditions under which Tsallis entropy and associated statistics apply, the following ones can be selected: - Anomalous diffusion. - Uniqueness theorem. - Sensitivity to initial conditions and entropy production at the edge of chaos. - Probability sets which make the nonadditiveTsallis entropy to be extensive in the thermodynamical sense. - Strongly quantum entangled systems and thermodynamics. - Thermostatistics of overdamped motion of interacting particles. - Nonlinear generalizations of the Schroedinger, Klein-Gordon and Dirac equations.

  32. Understanding Symmetry and DOF • RHIC is the best facility to study novel symmetries and critical point: • flexible machine to change conditions beam species (magnetic field), BES (turn on/off QGP) • Large Acceptance (good for both LPV and chiral symmetry) • Excellent lepton PID (both electrons and muons at midrapidity, who else has that!) • Since the beginning of physics, symmetry considerations have provided us with an extremely powerful and useful tool in our effort to understand nature. Gradually they have become the backbone of our theoretical formulation of physical laws. — Tsung-Dao LeeParticle Physics and an Introduction to Field Theory (1981), 177 • LPV: • beam energy:deconfinement, chiral symmetry • Beam species: magnetic field • Medium effect on vector mesons (chiral symmetry, resonant states): • beam energy; • Spectra and v2vsMl+l- • HFT+MTD+VTX upgrade 2017- • First glimpse of dilepton spectra around 0 and 1<M<3GeV • Heavy-flavor flow • Beyond 2017 • Phase II BES • sPHENIX • Detailed studies of DOF 还 黄鹤一去不复返

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