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Flow Effects on Jet Quenching with Detailed Balance

Flow Effects on Jet Quenching with Detailed Balance. Luan Cheng (Institute of Particle Physics, Huazhong Normal University) Introduction II. Potential Model with Flow Flow Effects on Parton Energy Loss with Detailed Balance Summary and Discussion Collaborator: Enke Wang

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Flow Effects on Jet Quenching with Detailed Balance

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  1. Flow Effects on Jet Quenching with Detailed Balance Luan Cheng (Institute of Particle Physics, Huazhong Normal University) • Introduction II. Potential Model with Flow • Flow Effects on Parton Energy Loss with Detailed Balance • Summary and Discussion Collaborator: Enke Wang ArXiv:0902.1896 [nucl-th]

  2. I. Introduction leading particle hadrons q q hadrons leading particle Leading particle suppressed hadrons q q hadrons leading particle suppressed Jet (hard probe) created by parton scattering before QGP is formed • high transverse momentum---”tomographically” hottest and densest phases of the reaction • calculable in pQCD p-p collision A-A collision Suppression of high Pt hadron spectra

  3. G-W (M. Gyulassy, X. –N. Wang) Model Nucl. Phys. B420 (1994) 583; Phys. Rev. D51 (1995) 3436 Static Color-Screened Yukawa Potential

  4. Radiated Energy Loss vs. Opacity First order in opacity contribution is dominant! Induced radiative energy loss:

  5. Detailed Balance Formulism (WW) B-E Enhancement Factor 1+N(k) Thermal Distribution Func. N(k) Stimulated Emission Thermal Absorption E. Wang & X.-N. Wang, Phys. Rev. Lett.87 (2001) 142301

  6. Numerical Result for Energy Loss • Intemediate large E, absorption is important • Energy dependence becomes strong • Very high energy E, net energy gain can be neglected

  7. Light Quark Energy Loss PHENIX, Nucl. Phys. A757 (2005) 184 Theoretical results from the light quark energy loss is consistent with the experimental data

  8. Motivation Flow Y Reaction plane Flow X QGP system is not static, it is a expanding system

  9. QED Static Charge: Coulomb electric field Moving Charge: electric and magnetic field Movement B QCD: Static Target: static color-electric field Moving Target: color-electric and color-magnetic field

  10. II. Interaction Potential with Flow system fixed at target parton: Static potential system for observer: Lorentz boost from system

  11. New Model Potential with Flow Four-vector potential : • The features of the new potential: • Collective flow produces a color-magnetic field • 2) non-zero energy transfor:

  12. III. Flow Effects on Parton Energy Loss with Detailed Balance Double Born Scattering k z z p 0 1 Elastic Scattering: Inelastic Scattering:

  13. Final-state Radiation Energy loss induced by thermal medium: = Net contribution: Energy gain Stimulated emission increase E loss Thermal absorption decrease E loss

  14. Feynman Diagram to the First Order in opacity

  15. Radiation Amplitude for Single Scattering Single scattering amplitude depends on the flow velocity along the jet direction

  16. Radiation Amplitude for Double Born Scattering Double Born scattering amplitude is related also with the flow velocity along the jet direction

  17. Radiation Probability to First Order in opacity Mean-free-path: Flow Effect Stimulated Emission Thermal Absorption Non-Abelian LPM Effect-Destructive Interference

  18. Gluon Formation Factor and Mean-free-path Gluon Radiation Formation Time: Gluon Formation Factor (LPM): Flow Effect In the presence of the collective flow in the positive (negative) jet direction, the formation time of gluon radiation becomes shorter (longer), the LPM effect is reduced (enhanced).

  19. Gluon Formation Factor and Mean-free-path Gluon Formation Factor (LPM): Mean-free-path: Flow Effect

  20. Energy Loss in First Order of Opacity QCD: QED: Energy loss induced by rescattering in thermal medium: Take limit: Zero Temperature Part: GLV Result Temperature-dependent Part: Flow Effect Energy gain

  21. Numerical Result for Energy Gain via Gluon Absorption • At large E region, • Energy gain decrese with increasing flow velocity in the positive jet direction • Very high energy E, energy gain can be neglected

  22. IV. Summary and Discussion Summary: 1) New potential for the interaction of a hard jet with the parton target has been derived, which can be used to study the jet quenching phenomena in the presence of collective flow of the QGP medium. 2) Collective flow along jet direction reduce the opacity, short the formation time of gluon radiation, increase gluon formation factor. 3) Collective flow has observable influence on the parton energy loss. For the flow velocity in the positive jet direction, jet energy loss decrease by 10-30%.

  23. Discussion • Collective flow effects affect the suppression of high Pt spectrum in high-energy heavy ion collision. • Collective flow effects affect anisotropy parameter v2 in high-energy heavy ion collision. • Our new potential can be used for heavy quark energy loss calculation and will alter the dead cone effect of heavy quark jet.

  24. Thank You

  25. Assumption • The targets are distributed with the density: • Opacity: Mean number of the collision in the medium • For a scattering center i:

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