Flow Effects on Dead Cone and Energy Loss of Heavy Quarks

Flow Effects on Dead Cone and Energy Loss of Heavy Quarks Luan Cheng Institute of Particle Physics, Huazhong Normal University Collaborator: Enke Wang 3rd Asian Triangle Heavy-Ion Conference Wuhan 19th, Oct. 2010

Outline • Background and Motivation • Dead Cone in Dynamic Medium • Heavy Quark Energy Loss with Flow • Summary

Leading particle suppressed Jet Quenching hadrons q q hadrons A-A collision leading particle suppressed I. Background Suppression of high Pt hadron spectra

Bjorken 1982: collisional energy loss • Gyulassy, Wang, et al. (90’s): radiative energy loss dominates • BDMPS, 1997, Energy loss ~ Nucl. Phys. B484:265, (1997) . • G-W Model, Opacity Expansion, Phys. Rev. Lett 85, 5535, (2000) Light Quark Energy Loss in a Static Medium Light hadrons suppression observed at RHIC is consisted with predictions from jet quenching theory.

STAR Charged hadrons from Light quark fragmentation Non-photonic electrons from heavy quark decays No Significant Difference BetweenHeavy Quark Jet and Light Quark Jet

Puzzle for Heavy Quark Energy Loss Heavy quark has less dE/dx due to suppression of small angle gluon radiation “Dead Cone” effect Y. Dokshitzer & D. Kharzeev PLB 519(2001)199 B. Zhang, E. Wang, X.-N. Wang, PRL93 (2004) 072301 M. Djordjevic , U. Heinz,Phys.Rev.Lett.101:022302,2008

M. Djordjevic, M. Gyulassy, Nucl.Phys.A733:265-298,2004 Motivation Where does “dead cone” come from? • Mass • Else? Propagation k No Dead Cone! p

M. Djordjevic, M. Gyulassy, Nucl.Phys.A733:265-298,2004 1. … 2. … Flow velocity v Dead cone in a Static Medium q very small two process contribute the same dead cone Static Medium Dynamic Medium

Dynamic Medium II. Dead Cone in Dynamic Medium1. Lorenz Boost Static Medium G-W Model Lorenz boost

1. … Flow velocity v Flow velocity v 2. Pole Shift Pole Shift 2. …

Dead Cone Reduce Significantly with Flow Triple Gluon Vertex Process

Summary of Dead Cone • 1. two dead cone • 2. one dead cone in a static medium is a special case • 3. dead cone decreases with • 4. contribution of triple gluon vertex process increases

LPM Effect in a Static Medium In a static medium Formation time of gluon radiation become shorter LPM effect is significantly reduced for heavy quark What is LPM Effect in a Dynamic Medium?

system for observer: Lorentz boost from system system fixed at target parton: Static potential III. Heavy Quark Energy Loss with Flow1. Interaction Potential with Flow

First Order in opacity Correction

Radiation Probability Gluon Formation Time:

GLV Result ArXiv:0902.1896 [nucl-th] Energy Loss vs. Flow Velocity Light Quark Energy Loss:

Average Flow Velocity and Effective Average Energy Loss Average Flow Velocity: 3D ideal Hydrodynamic simulation (T. Hirano et al, Phys. Rev. C65, 011901 (2001); Phys. Rev. C66, 054905 (2002); Phys. Lett. B636, 299 (2006).)for 0-10% central events of Au-Au collisions at RHIC energy:

Effective Average Energy Loss 3D ideal Hydrodynamic simulation for 0-10% and 40-60% central events of Au-Au collisions at RHIC energy

IV. Summary • Two dead cone in dynamic medium Static Medium is a special case • Flow reduces dead cone • Three gluon formation time • Heavy quark energy loss increases obviously in the presence of collective flow. • Little difference of b, c, light quarks in central collisions

Thank You

Flow Effects on Dead Cone and Energy Loss of Heavy Quarks