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Enke Wang (Institute of Particle Physics, Huazhong Normal University) with A. Majumder, X.-N. Wang I. Introduction II.Quark Recombination and Parton Fragmentation at zero temperature III.Quark Recombination and Parton Fragmentation in a Thermal Medium IV.Conclusion Nucl-th/0506040 Modified Fragmentation Function from Quark Recombination
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I. Introduction hadrons phph parton E are measured, and its QCD evolution tested in e + e -, ep and pp collisions Suppression of leading particles Fragmentation Function in Vacuum: Modification of Fragmentation Function in Medium: Jet Quenching
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Energy Loss in Cold Nuclear Matter from e-A DIS E. Wang, X.-N. Wang, Phys. Rev. Lett. 89 (2002) 162301
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Energy Loss in Hot Medium from Au-Au Collision PHENIX, Nucl. Phys. A757 (2005) 184 Energy loss (initial parton density) ~ 30 times larger than that in cold Au nuclei !
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Quark Recombination in intermediate Pt Region Intermediate Pt : Quark Recombination R. C. Hwa, C. B. Yang, PRC67 (2003) 034902 V. Greco, C. M. Ko, P. Levai, PRL90 (2003) 202302 R. J. Fries, B. Muller, C. Nonaka, S. A. Bass, PRL90 (2003) 202303 Baryon Meson Baryon Meson
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Motivation of the Work How to deal with the quark recombination from the quantum field theory? Is it possible to deal with the jet quenching and the recombination in a unified framework? This Work: Establish the theoretical framework of the quark recombination from the modification of fragmentation function in thermal medium.
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II. Quark Recombination and Parton Fragmentation at zero Temperature Single hadron fragmentation function: DGLAP:
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Meson state: Constitutent Quark Model Baryon state: Insert them into:
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Meson Production from Recombination (T=0) Recombination Probability: Constituent Diquark Distribution Function:
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Evolution of Double Constituent Quark Distribution Function DGLAP Equation of diquark distribution function: They have the same form as the single hadron fragmentation function ! Radiative correction to diquark distribution function:
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Sum Rule for Constituent Quark Distribution Function Single Constituent Quark Distribution Function: Diquark Distribution Function:
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III. Quark Recombination and Parton Fragmentation in a Thermal Medium Thermal Average: Single hadron fragmentation at finite T: J.Osborne, E.Wang, X.N.Wang PRD67 (2003) 094022 Difference with that at zero temperature: Depend on initial energy of parton and Temperature T Parton hadronize all together with the medium
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“Shower-Shower” & “Shower-Thermal” “Shower-Shower” Contribution: “Shower-Thermal” Contribution: Modified fragmentation function with energy loss in thermal medium
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“Thermal-Thermal” Contribution R. Fries, B. Muller, C. Nonaka, S. Bass, PRC68 (2003) 044902
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Baryon Production from Quark Recombination = + ++
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Fragmentation at extreme high Pt Extreme high transverse momentum: Fragmentation is dominant Baryon Meson
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VI. Conclusion 1.The hadron fragmentation function can be expressed as the convolution of the recombination probability and the constituent quark distribution function. 2.The DGLAP equation of the constituent quark distribution function is derived. The relation among triquark, diquark and single quark distribution function is obtained through sum rule. 3.Both thermal-shower recombination and parton energy loss lead to medium modification of parton fragmentation functions 4.A unified framework for parton energy loss and quark recombination
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Thank You Thank You
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Thermal Average of Matrix Element Shower-Shower Shower-Thermal Thermal-Thermal represents the modified fragmentation function with energy loss and detailed balance in hot medium
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Meson Production from Thermal Quark Recombination Meson fragmentation function at finite T:
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