1. Nu Xu1/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 High-Energy Nuclear Collisions and QCD Phase Structure Nu Xu (1) Nuclear Science Division, Lawrence Berkeley National Laboratory, USA (2) College of Physical Science & Technology, Center China Normal University, China

2. Nu Xu2/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Outline (1) Introduction - Strong interactions - Phase structure of QCD (2) Selected Results from RHIC - Penetrating probes: Jets and high p T phenomena - Bulk properties: collectivity and thermalization - Beam energy scan: explore the QCD phase structure - Physics of proton spin (3) Summary and Outlook - More discoveries at RHIC - Understand the dynamical evolution from cold nuclear matter to QGP: an Electron-Ion Collider (EIC) at RHIC

3. Nu Xu3/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Quantum ChromoDynamics 1)QCD is the basic theory for strong interaction. Its degrees of freedom, are well defined at short distance. 2)Little is known regarding the dynamical structures of matter that made from q, g. E.g. the confinement, nucleon spin, the QCD phase structure... Large α S and strong coupling – QCD at long distance. Short distance Long distance

4. Nu Xu4/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Confinement Potential T < T conf T > T conf constant potential linear potential r V(r,T) The strong interacting potential between quarks is a function of distance. It also depends on the temperature. 1) At low temperature, the potential increases linearly with the distance between quarks  quarks are confined. 2) At high temperature, the confinement potential is ‘melted’  quarks are ‘free’. Note: It is not clear yet at all if there is a critical ‘temperature’ in high energy collisions.

5. Nu Xu5/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Lattice QCD Predictions Left:Large increase in energy density at T C ~ 170 MeV. Not reach the non-interacting S.B. limit. Right: Heavy quark potentials are melted at high temperature. F. Karsch et al. Nucl. Phys. B524, 123(02). Z. Fodor et al, JHEP 0203:014(02). C.R. Allton et al, Phys. Rev. D66, 074507(02). F. Karsch, Nucl. Phys. A698, 199c(02). Temperature Distance Energy densityHeavy quark potential

6. Nu Xu6/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Phase Diagram QED QCD Phase Diagram: A map shows that, at given degrees of freedom, how matter organize itself under external conditions.

7. Nu Xu7/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 The QCD Critical Point - LGT prediction on the transition temperature T C 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 1 st 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

8. Nu Xu8/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 E. Fermi: “Notes on Thermodynamics and Statistics ” (1953) Neutron stars QCD Phase Diagram (1953) RHIC

9. Nu Xu9/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 (1, 2, 5-10)ρ 0 QCD Phase Diagram 1983 1983 US Long Range Plan - by Gordon Baym (1, 2, 5-10)*ρ 0 T C ~200 MeV

10. Nu Xu10/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 QCD Phase Diagram (2009) 1983 US Long Range Plan - by Gordon Baym nucl-th: 0907.4489, NPA830,709(09) L. McLerran nucl-th 0911.4806: A. Andronic, D. Blaschke, P. Braun-Munzinger, J. Cleymans, K. Fukushima, L.D. McLerran, H. Oeschler, R.D. Pisarski, K. Redlich, C. Sasaki, H. Satz, and J. Stachel Systematic experimental measurements (E beam, A) : Extract numbers that is related to the QCD phase diagram!

11. Nu Xu11/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006 RHIC BRAHMS PHOBOS PHENIX STAR AGS TANDEMS Relativistic Heavy Ion Collider Brookhaven National Laboratory (BNL), Upton, NY v = 0.99995  c = 186,000 miles/sec Au + Au at 200 GeV Animation M. Lisa

12. Nu Xu12/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Nu Xu Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006 12/59 STAR Collaboration

13. Nu Xu13/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Nu Xu Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006 13/59 Peripheral Event STAR Au + Au Collisions at RHIC (real-time Level 3)

14. Nu Xu14/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Nu Xu Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006 14/59 Au + Au Collisions at RHIC STAR Central Event (real-time Level 3)

15. (2) Selected Results from RHIC

16. Nu Xu16/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006 Energy Loss in A+A Collisions Nuclear Modification Factor: back-to-back jets disappear leading particle suppressed p+p Au + Au

17. Nu Xu17/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Suppression and Correlation In central Au+Au collisions: hadrons are suppressed and back-to-back ‘jets’ are disappeared. Different from p+p and d+Au collisions. Energy density at RHIC:  > 5 GeV/fm 3 ~ 30  0 Parton energy loss:J. Bjorken1982 (“Jet quenching”)Gyulassy & Wang 1992 …

18. Nu Xu18/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Hadron Suppression at RHIC Hadron suppression in more central Au+Au collisions!

19. y x pypy pxpx coordinate-space-anisotropy  momentum-space-anisotropy Anisotropy Parameter v 2 Initial/final conditions, EoS, degrees of freedom

20. Nu Xu20/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006 Higher Harmonics Higher harmonics are expected to be present. For smooth azimuthal distributions the higher harmonics will be small v n ~ v 2 n/2 v 4 - a small, but sensitive observable for heavy ion collisions. P. Kolb, PR C68, 031902(04) v 4 - magnitude sensitive to ideal hydro behavior. Borghini and Ollitrault, nucl-th/0506045 Peter Kolb, PRC 68, 031902

21. Nu Xu21/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 v 2 at Low p T Region - Minimum bias data! - At low p T, model result fits mass hierarchy well - Collective motion at RHIC - More work needed to fix the details in the model calculations. P. Huovinen, private communications, 2004

22. Nu Xu22/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011  -mesons Flow: Partonic Flow  -mesons are very special: - they do not re-interact in hadronic environment - they show strong collective flow - they are formed via coalescence with thermal s-quarks STAR: PRL 99, 112301(2007); Hwa and Yang, nucl-th/0602024; Chen et al., PRC73 (2006) 044903

23. Nu Xu23/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Collectivity, Deconfinement at RHIC - v 2 of light hadrons and multi-strange hadrons - scaling by the number of quarks At RHIC:  m T - NQ scaling  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

24. Nu Xu24/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Partonic Collectivity at RHIC! Partonic Collectivity at RHIC STAR: preliminary Shi: arXiv 0907.2265 QM09: arXiv 0907.2265

25. Nu Xu25/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Results on Anisotropic Flow 1)Stronger collectivity at LHC! 2)Initial eccentricity ε is largely uncertain From Kuma, Mohanty and ShiALICE arXie1011.3914

26. Nu Xu26/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Hadron Spectra from RHIC p+p and Au+Au collisions at 200 GeV sss ss uud ud Multi-strange hadron spectra are exponential in their shapes. STAR white papers - Nucl. Phys. A757, 102(2005). more central collisions 0-5%

27. Nu Xu27/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 The Thermal Model Assume thermally (constant T ch ) and chemically (constant n i ) equilibrated system at chemical freeze-out System composed of non-interacting hadrons and resonances Given T ch and m 's (+ system size), n i 's can be calculated in a grand canonical ensemble Obey conservation laws: Baryon Number, Strangeness, Isospin Short-lived particles and resonances need to be taken into account

28. Nu Xu28/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Yields Ratio Results - In central collisions, thermal model fit well with  S = 1. The system is thermalized at RHIC. - Short-lived resonances show deviations. There is life after chemical freeze-out. RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184. Thermal model fits data T ch = 163 ± 4 MeV  B = 24 ± 4 MeV

29. Beam Energy Scans at RHIC and LHC LHC: 2.76 – 5.4 TeV (Pb) (0.9 – 14 TeV (p)) RHIC: 200 – 5 GeV (Au) FAiR*/NICA: 11 – 4 GeV (Au) T: 180 – 55 MeV μ B : 5 – 800 MeV (tri-)Critical point Chemical freeze-out

30. Nu Xu30/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Hadron Spectra from RHIC p+p and Au+Au collisions at 200 GeV sss ss uud ud Multi-strange hadron spectra are exponential in their shapes. STAR white papers - Nucl. Phys. A757, 102(2005). more central collisions 0-5%

31. Nu Xu31/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Thermal Model Fits (Blast-Wave) Source is assumed to be: –Locally thermal equilibrated –Boosted in radial direction random boosted E.Schnedermann, J.Sollfrank, and U.Heinz, Phys. Rev. C48, 2462(1993) Extract thermal temperature T fo and velocity parameter  T 

32. Nu Xu32/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Blast Wave Fits: T fo vs.    1) , K, and p change smoothly from peripheral smoothly from peripheral to central collisions. to central collisions. 2) At the most central collisions,  T  reaches collisions,  T  reaches 0.6c. 0.6c. 3) Multi-strange particles ,  are found at higher T fo  are found at higher T fo and lower  T  and lower  T   light hadrons move  light hadrons move with higher velocity with higher velocity compared to strange compared to strange hadrons hadrons STAR: NPA715, 458c(03); PRL 92, 112301(04); 92, 182301(04). 200GeV Au + Au collisions

33. Nu Xu33/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Compare with Model Results 1) Hydro model works well for , K, p 2) Over-predicts flow for multi-strange hadrons 3) Initial ‘collective kick’ introduced (P. Kolb and R. Rapp, PRC67)

34. Nu Xu34/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Student Lecture, “Quark Matter 2006”, Shanghai, Nov. 14 - 20, 2006 Slope Parameter Systematics Partonic Hadronic

35. Nu Xu35/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Direct Radiation Measurements Expanding partonic matter at RHIC and LHC! Di-leptons allow us to measure the direct radiation from the matter with partonic degrees of freedom, no hadronization! - Low mass region: , ,   e - e + m inv  e - e + medium effect Chiral symmetry(?) - Intermediate region: J/   e - e + m inv  e - e + Direct radiation hadronic partonic Direct radiation: Hadronic Partonic

36. Nu Xu36/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Di-lepton Program at RHIC STAR Preliminary p T (GeV/c) ω ϕ J/ψ Key measurements: yields, mass, R AA, v 2  thermalization, thermal rates

37. Nu Xu37/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Correlations, Susceptibilities, Kurtosis Higher order correlations are correspond to higher power of the correlation length of the system: more sensitive to critical phenomena. Skewness: Symmetry of the correlation function. Kurtosis: Peakness of the correlation function. Connection to thermodynamics,  X. Skewness: Symmetry of the correlation function. Kurtosis: Peakness of the correlation function. Connection to thermodynamics,  X. S & K observables: total charge, total protons, net-p, net-Q S & K observables: total charge, total protons, net-p, net-Q M. A. Stephanov, PRL. 102, 032301 (09 ) R.V. Gavai and S. Gupta: 1001.2796. F. Karsch and K. Redlich, arXiv:1007.2581

38. Nu Xu38/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 High Order Correlations Event by event: 1.net-proton Kurtosis K p (E)* 2. two proton correlation functions C 2 (E) 3. ratio of the d/p 4. ratio of K/p * Gavai and Gupta, 03, 05; Gupta 0909.4630 M. Cheng et al. 08 Gupta, Karsch, Stephanov, INT, 08

39. Nu Xu39/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 High Moments: Critical Point Search  Measure conserved quantities, B, s, and Q.  First: High order fluctuation results consistent with thermalization.  First: Tests the long distance QCD predictions in hot/dense medium. Caveats: (a) static vs. dynamic; (b) net-B vs. net-p; (c) potential effects of freeze-out… - R. Gavai, S. Gupta, 1001. 3796 / F. Karsch, K. Redlich, 1007.2581 / M. Stephanov, 0911.1772. - STAR: PRL105, 02232(2010) and references therein.

40. Nu Xu40/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Summary and Outlook 1)High-energy nuclear collisions provide a unique tool for studying phase structure of matter, long distance QCD, with partonic degrees of freedom in the laboratory. 1)Next generation new experiments with high rate capabilities are important for the study of the QCD phase structure around the phase boundary: NA61 at SPS, CBM at FAiR and MPD at NICA. 2)Heavy Flavor Measurements: In order to determine the nature of thermalization at high-energy nuclear collisions, a systematic measurements for HF hadrons are necessary. 3)Electron-Ion Collider: In order to understand the dynamical evolution from cold nuclear matter to quark gluon plasma in high-energy nuclear collisions, a good understanding of the initial condition is necessary.

41. Nu Xu41/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 Quark Masses 1)Higgs mass: electro-weak symmetry breaking. (current quark mass) 2)QCD mass: Chiral symmetry breaking. (constituent quark mass) éStrong interactions do not affect heavy-quark masses. éImportant tool for studying properties of the hot/dense medium at RHIC. éTest pQCD predictions at RHIC. Total quark mass (MeV)

42. PHENIX-VTX: built and installed: c, b physics VTX Stripixel layer 4 STAR HFT PHENIC VTX

43. Nu Xu43/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 HFT: Charm Hadron v 2 and R AA - 200 GeV Au+Au m.b. collisions (500M events). - Charm hadron collectivity  light flavor thermalization Medium properties! - 200 GeV Au+Au m.b. collisions (|y|<0.5 500M events) - Charm hadron R AA  - Energy loss mechanism! - QCD in dense medium!

44. eSTAR ePHENIX eRHIC (EIC) 1) e-ring: 2 SRF LINAC, 1-5 GeV per pass, 4 (6) passes. 2) RHIC: 325 GeV p or 130 GeV Au with DX magnets removed. Coherent e-cooler eRHIC Detector injector 1)Study the partonic structure of cold nuclear matter at small-x 2)Parton distribution function of nuclear matter 3)Spin structure S. Vigdor: 2010 RHIC operational review

45. yr.101112131415161718192021 Timeline of QCD and Heavy Ion Facilities Spin STAR FGT BES RHIC-II STAR HFT eSTAR, EIC (eRHIC) US LRP FAIR CBM sis300 LHC NICA Others RHIC Spin Heavy Ion R&D Future programs J-PARC (50 GeV p+A) JLab (12 GeV upgrade) Nu Xu, September 2009

46. Many Thanks to the Organizers! Nu Xu

47. Nu Xu47/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 STAR Detector System TPC dE/dx PID: pion/kaon: p T ~ 0.6 GeV/c; proton p T ~ 1.2 GeV/c

48. Nu Xu48/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 RHIC: Polarized Hadron Collider Spin varies from rf bucket to rf bucket (9.4 MHz) Spin pattern changes from fill to fill Spin rotators provide choice of spin orientation “Billions” of spin reversals during a fill PHENIX AGS BOOSTER Spin Rotators (longitudinal polarization) Solenoid Partial Siberian Snake Siberian Snakes 200 MeV Polarimeter AGS Internal Polarimeter Rf Dipole RHIC pC Polarimeters Absolute Polarimeter (H  jet) AGS pC Polarimeters Strong Helical AGS Snake Helical Partial Siberian Snake Spin Rotators (longitudinal polarization) Spin flipper Siberian Snakes STAR Pol. H - Source LINAC

49. Nu Xu49/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 First W Asymmetry Measurement A L determination: 1)500 p+p collisions 2)First measurement A L via parity-violation in polarized proton-proton collisions. 3)W + : Observe directly u quark polarization! STAR: PRL, in print. arXiv: 1009.0326

50. Nu Xu50/45 Nanoscience and Quantum Physics 2011, Tokyo Institute of Technology, Japan, January 26 – 28, 2011 The First W Asymmetry Result Parity-violating single-spin asymmetry A L for W + /W - STAR Preliminary Run 9 (p+p √s=500 GeV) 1) TPC charge separation works up to p T ~ 50GeV 2) Measured asymmetries are in agreement with theory evaluations using polarized pdf’s (DSSV) constrained by polarized DIS data. STAR: PRL, in print. arXiv: 1009.0326