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Cheng LuanInstitute of Particle Physics,CCNU1 Jet Quenching in 1+1 Dimension Expanding Medium with Chemical Nonequilibrium Inst. of Particle Phys., CCNU.

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Presentation on theme: "Cheng LuanInstitute of Particle Physics,CCNU1 Jet Quenching in 1+1 Dimension Expanding Medium with Chemical Nonequilibrium Inst. of Particle Phys., CCNU."— Presentation transcript:

1 Cheng LuanInstitute of Particle Physics,CCNU1 Jet Quenching in 1+1 Dimension Expanding Medium with Chemical Nonequilibrium Inst. of Particle Phys., CCNU Cheng Luan August,2004

2 Cheng LuanInstitute of Particle Physics,CCNU2 1. Introduction 2. Parton Evolution 3.Jet Quenching in the 1+1 Expanding medium with Chemical Nonequilibrium 4.Numerical Results 5.Results Outline

3 Cheng LuanInstitute of Particle Physics,CCNU3 I. Introduction 1.Mot ivation: Quark matter produced in Relativistic Heavy Ion Collision at RHIC: * system is expanding * system may be in chemical nonequalibrium How about jet energy loss in the expansion system with chemical nonequalibrium?

4 Cheng LuanInstitute of Particle Physics,CCNU4 2. What is Jet Quenching? hadrons q q leading particle suppressed leading particle suppressed Jet Quenching

5 Cheng LuanInstitute of Particle Physics,CCNU5 3. Why chemical non-equilibrium? 1) Gluons “thermalize” very rapidly, reaching approximately isotropic momentum space distributions after a time of the order of 0.2fm/c. 2) Full equilibration of the gluon phase –space density takes considerably longer. Thermally equilibrium Chemical non-equilibrium

6 Cheng LuanInstitute of Particle Physics,CCNU6 II. Parton Evolution 1.Assume that the QGP has thermally equilibrated but is off from chemical equilibrium(Jutter distribution) If neglect the quantum corrections(Boltzmann approximation) If the result is obtained for the factorized Bose distribution (MFD approximation)

7 Cheng LuanInstitute of Particle Physics,CCNU7 Thermal quark Debye mass: MFD Juttner Boltzmann Here we use MFD approximation

8 Cheng LuanInstitute of Particle Physics,CCNU8 Consider the dominant processes The evolution of the parton densities governed by the master equations : Assume the expansion of the parton fireball is purely longitudinal For the1+1 dimension syestym :

9 Cheng LuanInstitute of Particle Physics,CCNU9

10 Cheng LuanInstitute of Particle Physics,CCNU10 2. If the matter is in thermal and chemical equilibrium. the quark(antiquark) and gluon distribution function should be: For the 1+1 dimension system which is in thermodynamical equilibrium,

11 Cheng LuanInstitute of Particle Physics,CCNU11 其中,

12 Cheng LuanInstitute of Particle Physics,CCNU12 III.Jet Quenching in the 1+1 Expanding Medium with Chemical Nonequilibrium Stimulated EmissionThermal Absorption B-E Enhancement Factor 1+f(k) Thermal Distribution Factor. f(k)

13 Cheng LuanInstitute of Particle Physics,CCNU13 Final-state Radiation

14 Cheng LuanInstitute of Particle Physics,CCNU14 Single direct rescattering: Double Born virtual interaction:

15 Cheng LuanInstitute of Particle Physics,CCNU15 reflects the destructive interference arising from The non-Abelian LPM effect. Thus, the radiation probability at the fist order in opacity including stimulated emission and thermal absorption is:

16 Cheng LuanInstitute of Particle Physics,CCNU16 In a 1+1 dimension expanding system, for a jet produced at point, at time, The opacity in direction is: Thus: jet1 jet2

17 Cheng LuanInstitute of Particle Physics,CCNU17 The parton energy loss induced by rescattering at the first order in opacity in the 1+1 dimension expanding medium become:

18 Cheng LuanInstitute of Particle Physics,CCNU18 Jet Energy loss in expansion system with chemical nonequalibrium

19 Cheng LuanInstitute of Particle Physics,CCNU19 Intermediate large E, absorption is important Energy dependence becomes strong Very high energy E, net energy gain can be neglected Detailed balance in expansion system with chemical nonequalibrium

20 Cheng LuanInstitute of Particle Physics,CCNU20 Jet Energy loss vs. initial fugacity

21 Cheng LuanInstitute of Particle Physics,CCNU21 If a parton produced at point, at time, loses the same energy in the equilibrated system as in the non-equilibrated system when propagating in a static medium. What will happen if they propagate in a 1+1 expanding medium?

22 Cheng LuanInstitute of Particle Physics,CCNU22 Parton energy loss in equilibrated system is larger than that in non- equilibrated system in the expansion medium. The ratio decreases with Increasing jet energy at fixed The ratio increases with Increasing at fixed E. (in static medium) Ratio of energy loss in expansion medium

23 Cheng LuanInstitute of Particle Physics,CCNU23 IV.Results 1.Absorption is important at intermediate large E in the 1+1 dimension expanding medium. Energy dependence becomes strong. 2.Parton energy loss is larger when the parton propagates in a equilibrated system than that in a chemical non-equilibrated system. 3.Parton energy loss in a chemical non-equilibrated system increases with E at fixed 4.The ratio of energy loss between equilibrated and non-equilibrated system decreases with increasing jet energy at fixed.The ratio increases with increasing at fixed E.

24 Cheng LuanInstitute of Particle Physics,CCNU24 Thank You Thank You


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