Heavy quark ”Energy loss" and ”Flow" in a QCD matter DongJo,Kim Jyväskylä University, Finland KPS 2007 Fall meeting 한국물리학회 2007 가을 October, 2007 Jeju Korea

OutlineOutline  Heavy Ion Physics  Centrality(Glauber model, R AA Flow (v 2 ))  Discoveries on light quark sector …..  Heavy quark measurement ( R AA, v 2 )  Theoretical guidelines  Summary

Oct DongJo Kim, KPS 2007 Fall2 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: ?

Oct DongJo Kim, KPS 2007 Fall3 Participants vs Binary collisions Participant = at least one inelastic collision Binary collision = point like scattering, optical theorem NxM

Oct DongJo Kim, KPS 2007 Fall4 HI collision - Nuclear Modification Factor R AA A+A n x m   N binary  varies with impact parameter b p+p

Oct DongJo Kim, KPS 2007 Fall5 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 Coordinate space Momentum space Initial Later PRL 91,

Oct DongJo Kim, KPS 2007 Fall6 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,

Oct DongJo Kim, KPS 2007 Fall7 dV PS quarks Elliptic anisotropy from the recombination Phys.Rev.Lett.91:092301,2003 Azimuthal prob. density distrib. of the quark field

Oct DongJo Kim, KPS 2007 Fall8 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. v2v2 baryons mesons

Oct DongJo Kim, KPS 2007 Fall9 PHENIX –Single electron measurements in p+p, d+Au, Au+Au, y~0  s NN = 130,200,62.4 GeV –Single muon measurements in p+p, d+Au,1<|y|<2  s NN = 200 GeV STAR –Direct D mesons hadronic decay channels in d+Au D 0  K π D ±  K ππ D* ±  D 0 π –Single electron measurements in p+p, d+Au Phys. Rev. Lett. 88, (2002) How to measure Heavy Flavor ?  Experimentally observe the decay products of Heavy Flavor particles (e.g. D- mesons) –Hadronic decay channels D  K  D 0       0 –Semi-leptonic decays D  e(  ) K  e MesonD ±,D 0 Mass1869(1865) GeV BR D 0 --> K +  - (3.85 ± 0.10) % BR D --> e + +X17.2(6.7) % BR D -->  +  +X 6.6 % PHENIX Preliminary (η = 0)

Oct DongJo Kim, KPS 2007 Fall10  S/B > 1 for p T > 1 GeV/c Run04: X=0.4%, Radiation length Run02: X=1.3% Signal/Background We use two different methods to determine the non-photonic electron contribution (Inclusive = photonic + non-photonic ) Cocktail subtraction – calculation of “photonic” electron background from all known sources Converter subtraction– extraction of “photonic” electron background by special run with additional converter (X = 1.7%) Cocktail subtraction – calculation of “photonic” electron background from all known sources Converter subtraction– extraction of “photonic” electron background by special run with additional converter (X = 1.7%) How to measure Heavy Flavor?  Charm/Bottom  electrons

Oct DongJo Kim, KPS 2007 Fall11 Systematic on the measurement Cocktail and converter analysis agrees very well Low pT : Converter High pT : Cocktail S/B > 1 for p T > 2 GeV/c PRL 97(2006) RICH Hadronic background Electrons E/p Signal/Background

Oct DongJo Kim, KPS 2007 Fall12 Heavy Flavor in Au+Au 200GeV  No suppression at low p T consistent with N scaling of total charm yield  Suppression observed for p T >3.0 GeV/c, smaller than for light quarks( R  AA ~ R charm AA ). PRL. 98, (2007)

Oct DongJo Kim, KPS 2007 Fall13 Non-photonic electron v 2 measurement  Non photonic electron v 2 is given as; v 2 γ.e ; Photonic electron v 2  Cocktail method (simulation) stat. advantage  Converter method (experimentally) v 2 e ; Inclusive electron v 2 => Measure R NP = (Non-γ e) / (γ e) => Measure (1) (2)

Oct DongJo Kim, KPS 2007 Fall14 Photonic e v 2 determination  good agreement converter method (experimentally determined)  photonic electron v 2 => cocktail of photonic e v 2 R = N X->e / N γe photonic e v 2 (Cocktail) decay v 2 (π 0 ) pT<3 ; π (nucl-ex/ ) pT>3 ; π 0 (PHENIX run4 prelim.)

Oct DongJo Kim, KPS 2007 Fall15 Non-zero charm v 2 ? (1)  Apply recombination model  Assume universal v 2 (p T ) for quark  simultaneous fit to v 2 π, v 2 K and v 2 non-γe [PRC Zi-wei & Denes] charm Shape is determined with measured identified particle v 2 universal v 2 (p T ) for quark a,b ; fitting parameters

Oct DongJo Kim, KPS 2007 Fall16 Non-zero charm v 2 ? (2)  χ 2 minimum ; a = 1, b = 0.96 (χ 2 /ndf = 21.85/27)  Based on this recombination model, the data suggest non-zero v 2 of charm quark. 2σ 4σ 1σ b ; charm a ; u χ 2 minimum result D->e

Oct DongJo Kim, KPS 2007 Fall17 Compare with models [PRB637,362] (1) Charm quark thermal + flow (2) large cross section ; ~10 mb (3) Resonance state of D & B in sQGP (4) pQCD [PRC72,024906] [PRC73,034913] [Phys.Lett. B ]

Oct DongJo Kim, KPS 2007 Fall18 Overview of Theoretical Framework  pQCD (1)  Radiative energy loss ( GLV, light quarks )  Collisional(elastic) energy loss ( additional 2x2 process )  Still pending issues not solved ( only R AA, Charm/Bottom Ratio )  Relative magnitude of elastic vs radiative loss channels  Non-perturbative pQCD (2)  Adding nonperturbative hadronic final state interaction effects  I.van Vite and A. Adil( Collisional dissociation, R AA )  Van Hees ( recombination, R AA and v 2 )  AdS/CFT Related (3)  Partonic radiative transport coeff ( ) : H.Liu, K.Rajagopal,U.A. Wiedemann  Diffusion coefficient(D HQ ), R AA and v 2 ) : G.D. Moore, D.Teany  W. Horowitz ( more like direct calculation according to ads/CFT )  Double ratio ( R AA (charm)/R AA (bottom) )  Comparison with pQCD

Oct DongJo Kim, KPS 2007 Fall19 Shear Viscosity(  ) to Entropy density( s ) ratio  Shear Viscosity(  ) to Entropy density( s ) ratio  /s ~ 1/4  (4)  Diffusion coefficient(D HQ ), R AA and v 2 ) : G.D. Moore, D.Teany  Elastic scattering and resonance excitation : Van Hees  Ads/CFT itself  Hydrodynamics

Oct DongJo Kim, KPS 2007 Fall CTEQ SS - Cacciari Heavy quark mass Suppress radiation in a cone of Θ < m Q /E Dead cone effect No collinear divergence Heavy quarks as a probe parton hot and dense medium light M.Djordjevic PRL 94 (2004) ENERGY LOSS

Oct DongJo Kim, KPS 2007 Fall21 Elastic energy loss S. Wicks et al., nucl-th/ Partonic Energy Loss Radiative 2  N processes. Final state QCD radiation as in vacuum (p+p coll) - enhanced by QCD medium. Elastic 2  2 LO processes Elastic  E models predict significant broadening of away-side correlation peak - not seen in the data. Also various models differ significantly in radiative/elastic fraction.

Oct DongJo Kim, KPS 2007 Fall22 Electrons Pions  s =.3 First results indicate that the elastic energy loss may be important M. G. Mustafa, Phys.Rev.C72:014905,2005 (1)PHENIX,PRL. 98, (2007) (2) M. G. Mustafa, Phys.Rev.C72:014905,2005 Elastic energy loss is becoming important?

Oct DongJo Kim, KPS 2007 Fall23 Fragmentation and dissociation of hadrons from heavy quarks inside the QGP 25 fm 1.6 fm 0.4 fm B D QGP extent (3)I. Vitev (A.Adil, I.V., hep-ph/ ), Phys Lett B Collisional dissociation ?

Oct DongJo Kim, KPS 2007 Fall24 HQ Energy Loss and Flow  Two models describes strong suppression and large v 2 simultaneously Rapp and Van Hees Phys.Rev.C71:034907,2005 Elastic scattering : small τ D HQ × 2πT ~ Moore and Teaney Phys.Rev.C71:064904,2005 D HQ × 2πT = 3~12  Recall  +p = T s at  B =0 This then gives  /s ~(1.5-3)/4  Within factor of 2 of conjectured bound Phys.Rev.D74, ,2006 PRL. 98, (2007)

Oct DongJo Kim, KPS 2007 Fall25 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(perfect, inviscid) fluid   =0 String theory approach: Strongly interacting matter  AdS/CFT duality  (Phys. Rev. Lett., 2005, 94, ) What can we learn from the data ?

Oct DongJo Kim, KPS 2007 Fall26 Universal  /s P.Kovtun, D.Son, A.S., hep-th/ , hep-th/ Minimum of in units of

Oct DongJo Kim, KPS 2007 Fall27 (  /s) min in units of T.Schafer, cond-mat/ Chernai, Kapusta, McLerran, nucl-th/ ~23 ~8.8 a trapped Fermi gas ~25 ~ 4.2 QCD

Oct DongJo Kim, KPS 2007 Fall28 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

Oct DongJo Kim, KPS 2007 Fall29 AdS/CFT and pQCD at LHC Double ratio of charm and bottom quark suppression promising window for AdS/CFT models. W.Horowitz Gyulassy arXiv:

Oct DongJo Kim, KPS 2007 Fall30 SummarySummary  Electron R AA & v 2 mainly from charm  s = 200 GeV in Au+Au collisions at RHIC-PHENIX  Similar suppression as light quarks at high pT  Large v2 is observed  Charm quark strongly coupled to the matter  Model comparison suggests  Small τ and/or D HQ are required  η /s is very small, near quantum bound.  AdS/CFT will help the problems in pQCD or something else we will find ?  Direct measurement of Charm/Bottom with PHENIX upgrade and D/B Factory at LHC

Oct DongJo Kim, KPS 2007 Fall31 AdS/CFT Correspondence hep-th/ Put FD/String too here