JetDiscovery of Jet Quenching and BeyondXin-Nian WangLBNL, June 29, 05

Discovery of Jet Quenching and BeyondIntroduction: A brief historyJet quenching pattern and implicationsBeyond the discovery of jet quenchingXin-Nian Wang (LBNL)Shanghai, June 28-29, 2005 The 59th Eastern Forum on Science and Technology

Jet TomographyDynamic System: Photon or dilepton emissionJ/Y suppression

A Chronicle of Jet Quenching 1982, Bjorken (unpublished): elastic dE/dx too small1990,Gyulassy, Pluemer: Evoking inelastic dE/dx1992, Gyulassy, XNW: Suppression of leading hadrons due to jet quenching1994, Gyulassy, XNW: First calculation of radiative parton energy loss with LPM1995, Gyulassy, Pluemer, XNW: Estimate of mono-jet rate in AA at RHIC1996, Huang, Sarcevic, XNW: Medium modified fragmentation function & gamma tagged jet quenching1996, Zakharov: Path integral formulation of dE/dx1997, Baier et al: non-abelian LPM in QCD- interaction with gluonic clouds

A Chronicle- Con d 2000, XNW: First estimate of Cronin at RHIC2000, Gyulassy, Levai, Vitev: Opacity expansion I.2001, Wiedemann: Opacity expansion II2001, Guo, XNW: Higher-Twist expansion and calculation of modified frag. function.2001, XNW, GVW: high pT v2 due to jet quenching 2002: Suppression of high pT hadron in Au+Au2003: v2 at high pt observed 2003: Suppression of back-side jet2003, June 18: d+Au results announced2004, azimuthal dependence of away-side jet2005, angular correlations within jets

Jet Quenching Jet Quenching Suppression of high pT jet in dense medium Experimentally: Medium modification of jet fragmentation function (FF)Suppression of the leading hadrons in FFTheoretically: Parton energy loss before hadronization Or absorption of leading hadrons from jets

Single Spectra Suppression

Away-side suppression or Mono-jet

Azimuthal Anisotropy

Non-suppression in p+ASystematic study of high p(T) hadron spectra in p p, p A and A A collisions from SPS to RHIC energiesPhys. Rev. C 61, 064910 (2000) hep-ph/9812021, XNW

Experimental Evidence

Modified Fragmentation Function

Energy LossTwo-parton correlation:Quark energy loss = energy carried by radiated gluon

Single spectra in A+A collisionsParticipantDensitySingle spectra

Nuclear Modification FactorWang&Wang2001

Single hadron suppression

Suppression of away-side jet

Azimuthal AnisotropySingle hadronIntermediate pT: effects of parton coalescence

Partonic Energy Loss at RHICE=10 GeVEnke Wang & XNW2000

Beyond the discovery I: Energy Dependence of quenchingD. dEnterria, Hard Probes 200463 GeV

Effect of non-Abelian energy lossDEg=DEqDEg=2DEqQun Wang & XNW 04

Beyond the Discovery IIdihadronAzimuthal Mapping of jet quenching

Beyond the discovery III: Measuring Parton Energy LosspTtrig

Beyond the discovery V: Mod. FF

Beyond the discovery IV: Abnormal angular distribution

SummaryDiscovery of Jet Quenching proves that dense matter is formedJet quenching is caused by partonic energy lossDense matter at RHIC is 30 times higher than cold nucleiThe matter is strongly interactiveJet tomography become useful and power tool for studying properties of dense matter

Theoretical work in ChinaEnke Wang, Benwei Zhang, Hanzhong Zhang, W.C. Xiang etc (IOPP, Wuhan)S.Y. Li, Z.G. Shi (Shandong Univ.)Qun Wang (USTC)Collaboration with experimental groups

The discovery of Jet Quenching at RHIC points to the formation of extremely dense and hot matter produced at RHIC. This lays down the foundation of future studies of properties of the dense matter using Jet Tomography Theory developed at LBNL.For jet quenching, the discovery phase is almost over. It becomes powerful tool we use to study the properties of dense matter in heavy-ion collisions. Today, the picture we get from jet tomography is much clearer that we could see a year ago. I would like to discuss here today what have seen so far.From the beginning, theorists have worked along the line of parton energy loss and medium modification of jet fragmentation function. There are basically four corner stones in the experimental observation of jet quenchingThough, theoretical understanding of parton energy loss was not very clear at early times, one can estimate the effects given the energy lossFour cornerstones for the discovery jet quenching and provide a platform to build powerful tools for studying dense matter

To quantitatively picture the dense matter through, jet quenching, we need first to understand how jet fragmentation is modified in mediumAsymptotic form of parton energy loss