7-Jun-15Jan Rak, HEP Heavy Ion Physics Experimental Overview Jan Rak Jan Rak Jyväskylä University & Helsinki Institute of Physics, Finland Experimentalist point of view

7-Jun-152 Heavy Ion Physics old paradigm Exploring Phases and Structures of QCD phase diagram – High temperature T – High density  – Many-body aspects QCD – Vacuum properties RHIC LHC hot & dense & net baryon free q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q

7-Jun-15Jan Rak, HEP Heavy Ion Physics 2005  new paradigm Heavy Ion - test laboratory for string theory Shear viscosity “ Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics” P.K. Kovtun, D.T. Son, and A.O. Starinets Quenching parameter “ Calculating the jet quenching parameter from AdS/CFT” Liu, Rajagopal, and Wiedemann Thermal particle production Unruh mechanism, Karzeev, Satz Robi Peschanski parallel talk on Thursday

7-Jun-15Jan Rak, HEP Phase transition in Heavy Ion collisions T.D.Lee (1974) Temporarily restored broken symmetries of the physical vacuum Collins, Perry (1975) Asymptotic freedom in QCD  deconfined quarks/gluons matter E.V. Shuryak (1978) Invented Quark Gluon Plasma  target of HI community 0.2 fm 0.02 fm fm strong coupling  S (Q) Infrared Slavery Asymptotic Freedom  T = MeV  ~ GeV/fm 3 T = MeV  ~ GeV/fm 3 Lattice QCD, Lect. Notes Phys 583, 209 (2002) Ideal gas limit

7-Jun-15Jan Rak, HEP HI - Center Of Mass Energy regimes HI - Center Of Mass Energy regimes 80s AGS  s  4 GeV USA 90s SPS  s  17 GeV CERN 4x 2000 RHIC  s  200 GeV USA 11x 8x 2008 LHC pp  s  14 TeV 2008 LHC AA  s  5.5 TeV CERN 27x Relativistic Heavy Ion Collider Brookhaven Nat. Lab. Long Island, USA SPS era: Smoking gun wanted RHIC era: sQGP discovered LHC era: ?

7-Jun-15Jan Rak, HEP HI collision - Nuclear Modification Factor R AA A+A n x m   N binary  varies with impact parameter b p+p

7-Jun-15Jan Rak, HEP SPS  s = 17 GeV RHIC  s = 200  o data  s=17 GeV Although there were hints for anomalous behavior of nuclear matter at SPS (see CERN press. Rel. 2000) J/  supp., dilepton enhanc., prompt  No light pion suppression observed.

7-Jun-15Jan Rak, HEP p-p collisions at RHIC:  0 production (PHENIX) 19% norm uncertainty NLO pQCD agrees with data arXiv: v1 [hep-ex] Phys. Rev. Lett., 2006, 97,  s=200GeV

7-Jun-15Jan Rak, HEP 00 00 RHIC  s = 200  o and h + +h - data d Au 00 Strong suppression (x5) in central Au+Au coll. No suppression in peripheral Au+Au coll. No suppression (Cronin enhancement) in control d+Au exp. Convincing evidence for the final state partonic interaction - emergence of sQGP Strong suppression (x5) in central Au+Au coll. No suppression in peripheral Au+Au coll. No suppression (Cronin enhancement) in control d+Au exp. Convincing evidence for the final state partonic interaction - emergence of sQGP

7-Jun-15Jan Rak, HEP QCD and Jets At the famous Snowmass conf. (July 1982) almost nobody believed that jets seen in e+e collisions exist also in p+p. NA5 data - no jet structure. The International HEP conference in Paris, three weeks later, changed everything. C. DeMarzo et al NA5, PLB112(1982)173 Full azim. trigg. b-2-b trigg. QCD This one event from UA2 in 1982 changed everybody’s opinion.

7-Jun-15Jan Rak, HEP Status of R AA in AuAu at  s NN =200 GeV Direct  are not suppressed.  0 and  suppressed even at high p T Implies a strong medium effect (energy loss) since  not affected. Suppression is flat at high p T. Direct  are not suppressed.  0 and  suppressed even at high p T Implies a strong medium effect (energy loss) since  not affected. Suppression is flat at high p T.

7-Jun-15Jan Rak, HEP For Au+Au min bias direct  R AA is simple Au+Au minimum bias at mid-rapidity Do the structure function ratios actually drop by ~20% from x=0.1 to x=0.2? Eskola,Kolhinen,Ruuskanen Nucl. Phys. B535(1998) x T x Eskola et al. NPA696 (2001) 729 gluons in Pb / gluons in p Anti Shadowing

7-Jun-15Jan Rak, HEP The biggest result at QM2006? If R  AA = R  AA the whole concept of energy loss changes: perhaps no effect for pT>20 GeV. New physics on the horizon? If R  AA = R  AA the whole concept of energy loss changes: perhaps no effect for pT>20 GeV. New physics on the horizon? p+p  +X reference From FNAL, SPS, ISR extrapolation our own measurement

7-Jun-15Jan Rak, HEP More cracks in the ice ? J/  heavy quarks

7-Jun-15Jan Rak, HEP J/  Suppression--R AA PHENIX mid-rapidity (e+e-) the same as NA50!!! NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) Suppression increases at more forward rapidity PHENIX PRL 98, (2007) Less dense medium More dense medium

7-Jun-15Jan Rak, HEP Heavy quarks as a probe Due to large mass heavy quarks are primarily produced by gluon fusion  sensitive to initial gluon distribution M. Gyulassy and Z. Lin, PRC 51, 2177 (1995) Heavy quarks lose less energy due to suppression of small angle gluon radiation (dead-cone effect) Dokshitzer and Kharzeev, PLB 519, 199 (2001) parton hot and dense medium light M.Djordjevic PRL 94 (2004) ENERGY LOSS Phys.Rev.Lett.98:172301,2007 J. Bielcik Thursday parallel pres.

7-Jun-15Jan Rak, HEP Inclusive probes summary We observed: Huge suppression of light mesons in central Au+Au collisions No suppression in d+Au and peripheral Au+Au coll. Similar suppression of J/  at RHIC as at SPS Similar suppression for heavy and light quarks Concluded: Deconfined opaque partonic matter has been produced. Let’s look at more dynamical observables azimuthal anisotropy of produced hadrons (Flow)

7-Jun-15Jan Rak, HEP Nuclear Geometry and Hydrodynamic flow  RP multiple scattering larger pressure gradient in plane less yield out more in plane less yield out more in plane x y z Reaction Plane Spatial asymmetry eccentricity Mom. Asymmetry elliptic flow

7-Jun-15Jan Rak, HEP v2v2 baryons mesons “Fine structure” of v2(pT) for different mass particles. In Ideal “hydro” picture: What are the relevent DOF’s in “Flow” ? v2(KE T ) universal for baryons v2(KE T ) universal for mesons Do we have an even more universal scaling? v 2 (p T )  v 2 (KE T ) Phys. Rev. Lett., 2007, 98,

7-Jun-15Jan Rak, HEP QG medium fragmentation-quark recombination dV PS quarks pt 3 quarks 1 proton Why is the universal v 2 (KE T ) different for meson and baryons? Exited quark-gluon medium  huge phase-space densities  constituent Quark Recombination / Coalescence Phys. Lett.,1996,B371, FERMILAB hep-ex/ Phys.Rev.Lett.91:092301,2003

7-Jun-15Jan Rak, HEP v2v v 2 /n q The “Flow” Knows Quarks Assumption: all bulk particles are coming from recombination of flowing partons Discovery of universal scaling : ● flow parameters scaled by quark content n q resolves meson-baryon separation of final state hadrons. Works for strange and even charm quarks. ● strongly suggests the early thermalization and quark degree of freedom.

7-Jun-15Jan Rak, HEP Jet shape evolution with trigger and assoc. p T Au+Au / p+p  s = 200 GeV arXiv: [nucl-ex] Per-trigger yield vs.  for various trigger and partner p T (p A T  p B T ), arranged by increasing pair momentum (p A T + p B T ) d+Au p + p  jet + jet 

7-Jun-15Jan Rak, HEP Is the quark matter really perfect fluid? Viscosity  then defined as. In the standard picture reflects the transport properties of multi-particle system.  small viscosity → Large cross sections  Large cross sections → strong couplings  Strong couplings → perturbation theory difficult ! Ideal fluid   =0 String theory approach: Strongly interacting matter  AdS/CFT duality  (Phys. Rev. Lett., 2005, 94, ) What can we learn from the data ?

7-Jun-1524 Viscosity from the data at RHIC Phys. Rev., 2003, C68, Phys. Rev. Lett., 2007, 98, Temperature T=160 MeV Mean free path (transport sim.) f =0.3  0.03 fm Speed of sound c s =0.35  0.05

7-Jun-15Jan Rak, HEP Jet Quenching: AdS/CFT or pQCD ? Jet Quenching: AdS/CFT or pQCD ? “Testing AdS/CFT Deviations from pQCD Heavy Quark Energy Loss with Pb+Pb at LHC 2007 “Horowitz Gyulassy arXiv: Energy loss : 1. pQCD fractional momentum loss for Heavy Quark: Djordjevic, Gyulassy Nucl.Phys.A733: ,2004 – independent of p T ans stronger dependence on M Q ! –T 2 dependence in exponent makes for a very sensitive probe –Expectation:  pQCD  0 at high p T vs  AdS is independent of p T ! 2. String theory momentum loss for Heavy Quark: Gubser, Herzog et al

7-Jun-15Jan Rak, HEP AdS/CFT and pQCD at LHC LHC is the D and B factory - should and will be easy to measure! Double ratio of charm and bottom quark suppression promising window for AdS/CFT models.

7-Jun-15Jan Rak, HEP …..

7-Jun-15Jan Rak, HEP SummarySummary RHIC provided us the high precision data which indicate: –High density deconfined matter is produced –Quark DOFs observed (v 2 scaling) –Fast thermalization –Small viscosity (strongly coupled matter) Open questions: –Heavy and light quark suppression similarity –Prompt photon suppression at high-p T –J/  suppression similar at RHIC (  s=200GeV) and SPS (  s=17GeV) –J/  suppression at RHIC larger at forward rapidity New physics is under exploration –HI collisions provide a testbed for “applied string physics” LHC data will be crucial for further exploration of new directions. sQGPsQGP

7-Jun-15Jan Rak, HEP PHENIX milestone: signal of chiral dynamics Subm. to Phys. Rev. Lett arXiv:  symmetry broken quark condenste  250 MeV 3  symmetry restored Brown-Rho quark condenste  0 MeV 3 Rulled out NA60  s=17 GeV

7-Jun-15Jan Rak, HEP th PHENIX milestone: signal of chiral dynamics Subm. to Phys. Rev. Lett arXiv: low mass dilepton excess at RHIC! yield grows faster than Npart excess > r modification  symmetry broken quark condenste  250 MeV 3  symmetry restored Brown-Rho quark condenste  0 MeV 3 Rulled out

7-Jun-15Jan Rak, HEP Comparison: ρ mass modification R.Rapp, Phys.Lett. B 473 (2000) R.Rapp, Phys.Rev.C 63 (2001) R.Rapp, nucl/th/ calculations for min bias QGP thermal radiation included Broad range enhancement 150 < m ee < 750 MeV 3.4±0.2(stat.) ±1.3(syst.)±0.7(model ) submitted to Phys. Rev. Lett arXiv: