1. Introduction to Relativistic Heavy Ion Collision Physics Huan Z. Huang 黄焕中 Department of Physics and Astronomy University of California, Los Angeles

2. Two Puzzles of Modern Physics Missing Symmetry – all present theories are based on symmetry, but most symmetry quantum numbers are NOT conserved. Unseen Quarks – all hadrons are made of quarks, yet NO individual quark has been observed. -- T.D.Lee 李政道

3. Vacuum As A Condensate Vacuum is everything but empty! The complex structure of the vacuum and the response of the vacuum to the physical world breaks the symmetry. Vacuum can be excited! We do not understand vacuum at all !

4. A Pictorial View of Micro-Bangs at RHIC Thin Pancakes Lorentz  =100 Nuclei pass thru each other < 1 fm/c Huge Stretch Transverse Expansion High Temperature (?!) The Last Epoch: Final Freezeout-- Large Volume Au+Au Head-on Collisions  40x10 12 eV ~ 6 micro-Joule Human Ear Sensitivity ~ 10 -11 erg = 10 -18 Joule A very loud Bang, indeed, if E  Sound…… Vacuum Engineering !

5. initial state pre-equilibrium QGP and hydrodynamic expansion hadronization hadronic phase and freeze-out High Energy Nucleus-Nucleus Collisions Physics: 1) Parton distributions in nuclei 2) Initial conditions of the collision 3) a new state of matter – Quark-Gluon Plasma and its properties 4) hadronization

6. RHIC Complex

7. STAR Relativistic Heavy Ion Collider --- RHIC Au+Au 200 GeV N-N CM energy Polarized p+p up to 500 GeV CM energy

8. Salient Feature of Strong Interaction Asymptotic Freedom: Quark Confinement: 庄子天下篇 ~ 300 B.C. 一尺之棰，日取其半，万世不竭 Take half from a foot long stick each day, You will never exhaust it in million years. QCD qq qq q q Quark pairs can be produced from vacuum No free quark can be observed Momentum Transfer Coupling Strength Shorter distance  (GeV)

9. QCD on Lattice Transition from quarks to hadrons – DOF ! QGP – not an ideal Boltzmann gas !

10. Lattice: current status technical progress: finer mesh size, physical quark masses, improved fermion actions  phase-transition: smooth, rapid cross-over  EoS at finite μ B : in reach, but with large systematic uncertainties  critical temperature: T C  180 MeV Rajagopal & Wilczek, hep-ph/0011333 Fodor & Katz, hep-lat/0110102

11. Quark-Hadron Phase Transition

13. The Melting of Quarks and Gluons -- Quark-Gluon Plasma -- Matter Compression:Vacuum Heating: High Baryon Density -- low energy heavy ion collisions -- neutron star  quark star High Temperature Vacuum -- high energy heavy ion collisions -- the Big Bang Deconfinement

14. Collision Dynamics

15. Initial Energy Density Estimate PRL 85, 3100 (00); 91, 052303 (03); 88, 22302 (02), 91, 052303 (03) PHOBOS hminus: Central Au+Au =0.508GeV/c pp: 0.390GeV/c Pseudo-rapidity Within |  |<0.5 the total transverse momentum created is 1.5x650x0.508 ~ 500 GeV from an initial transverse overlap area of  R 2 ~ 153 fm 2 ! Energy density  ~ 5-30  0 at early time  =0.2-1 fm/c ! 19.6 GeV 130 GeV 200 GeV

16. Ideas for QGP Signatures Strangeness Production: (J.Rafelski and B. Muller PRL 48, 1066 (1982)) s-s quark pair production from gluon fusions in QGP leads to strangeness equilibration in QGP  most prominent in strange hyperon production (  and anti-particles). Parton Energy Loss in a QCD Color Medium: (J.D. Bjorken Fermilab-pub-82-059 (1982) X.N. Wang and M. Gyulassy, PRL 68, 1480 (1992)) Quark/gluon dE/dx in color medium is large!

17. Ideas for QGP Signatures Chiral Symmetry Restoration: T = 0, m(u,d,s) > 0 – Spontaneous symmetry breaking T> 150 MeV, m=0 – Chiral symmetry restored Mass, width and decay branching ratios of resonances may be different in dense medium. QCD Color Screening: (T. Matsui and H. Satz, Phys. Lett. B178, 416 (1986)) A color charge in a color medium is screened similar to Debye screening in QED  the melting of J/ . cc Charm quarks c-c may not bind Into J/  in high T QCD medium The J/  yield may be increased due to charm quark coalescence at the final stage of hadronization (e.g., R.L. Thews, hep-ph/0302050)

18. 1 st year detectors Silicon Vertex Tracker Central Trigger Barrel FTPCs Time Projection Chamber Barrel EM Calorimeter Vertex Position Detectors Endcap Calorimeter Magnet Coils TPC Endcap & MWPC + TOF Silicon Strip Detector ZDC 2 nd year detectors installation in 2002 installation in 2003 ZDC The STAR Detector