Enke Wang (Institute of Particle Physics, Huazhong Normal University) with A. Majumder, X.-N. Wang...
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Transcript of Enke Wang (Institute of Particle Physics, Huazhong Normal University) with A. Majumder, X.-N. Wang...
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
I. Introduction
hadrons
ph
parton
E
),,()(0 EzDzD ahah
)(0 zDah
are measured, and its QCD evolutiontested in e+e-, ep and pp collisions
Suppression of leading particles
Fragmentation Function in Vacuum:
Modification of Fragmentation Function in Medium:
),1
(1
1),( 0
z
zD
zEzD ahah
Jet Quenching
Energy Loss in Cold Nuclear Matter from e-A DIS
0.5 GeV/fmdE
dx
E. Wang, X.-N. Wang, Phys. Rev. Lett. 89 (2002) 162301
Energy Loss in Hot Medium from Au-Au Collision
PHENIX, Nucl. Phys. A757 (2005) 184
fmGeVdx
dE8.13
Energy loss (initial parton density) ~ 30 times larger than that in cold Au nuclei !
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
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.
II. Quark Recombination and Parton Fragmentation at zero Temperature
Single hadron fragmentation function:
DGLAP:
Meson Production from Recombination (T=0)
Recombination Probability:
Constituent Diquark Distribution Function:
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:
Sum Rule for Constituent Quark Distribution Function
Single Constituent Quark Distribution Function:
Diquark Distribution Function:
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
“Shower-Shower” & “Shower-Thermal”
“Shower-Shower” Contribution:
“Shower-Thermal” Contribution:
Modified fragmentation function with energy loss in thermal medium
Fragmentation at extreme high Pt
Extreme high transverse momentum:
01
1/||
TpTe)|(| TpT
Fragmentation is dominant
Baryon
Meson
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
Thermal Average of Matrix Element
Shower-Shower
Shower-ThermalThermal-Thermal
represents the modified fragmentation function with energy loss and detailed balance in hot medium