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Title: Bulk viscosity of strongly interacting matter in the relaxation time approximation

Here, we show how thermal mean field effects can be incorporated consistently in the hydrodynamical modeling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio of the bulk viscosity to its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the β λ function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cutoff. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of ς/τ R for gases obeying Bose-Einstein statistics.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [2]
  1. McGill Univ., Montreal, QC (Canada); Jan Kochanowski Univ., Kielce (Poland)
  2. McGill Univ., Montreal, QC (Canada)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-205755-2018-JAAM
Journal ID: ISSN 2469-9985; PRVCAN
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 97; Journal Issue: 4; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
OSTI Identifier:
1454832
Alternate Identifier(s):
OSTI ID: 1434403

Czajka, Alina, Hauksson, Sigtryggur, Shen, Chun, Jeon, Sangyong, and Gale, Charles. Bulk viscosity of strongly interacting matter in the relaxation time approximation. United States: N. p., Web. doi:10.1103/PhysRevC.97.044914.
Czajka, Alina, Hauksson, Sigtryggur, Shen, Chun, Jeon, Sangyong, & Gale, Charles. Bulk viscosity of strongly interacting matter in the relaxation time approximation. United States. doi:10.1103/PhysRevC.97.044914.
Czajka, Alina, Hauksson, Sigtryggur, Shen, Chun, Jeon, Sangyong, and Gale, Charles. 2018. "Bulk viscosity of strongly interacting matter in the relaxation time approximation". United States. doi:10.1103/PhysRevC.97.044914.
@article{osti_1454832,
title = {Bulk viscosity of strongly interacting matter in the relaxation time approximation},
author = {Czajka, Alina and Hauksson, Sigtryggur and Shen, Chun and Jeon, Sangyong and Gale, Charles},
abstractNote = {Here, we show how thermal mean field effects can be incorporated consistently in the hydrodynamical modeling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio of the bulk viscosity to its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the βλ function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cutoff. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of ς/τR for gases obeying Bose-Einstein statistics.},
doi = {10.1103/PhysRevC.97.044914},
journal = {Physical Review C},
number = 4,
volume = 97,
place = {United States},
year = {2018},
month = {4}
}