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 heavyion collisions. The nonequilibrium correction to the distribution function resulting from a temperaturedependent 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 BoseEinstein gases within the ChapmanEnskog and 14moment approaches in the relaxation time approximation. Constant and temperaturedependent 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 temperaturedependent 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 BoseEinstein 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 BoseEinstein statistics.
 Authors:

^{[1]};
^{[2]};
^{[3]};
^{[2]};
^{[2]}
 McGill Univ., Montreal, QC (Canada); Jan Kochanowski Univ., Kielce (Poland)
 McGill Univ., Montreal, QC (Canada)
 Brookhaven National Lab. (BNL), Upton, NY (United States)
 Publication Date:
 Report Number(s):
 BNL2057552018JAAM
Journal ID: ISSN 24699985; 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 24699985
 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) (SC26)
 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 heavyion collisions. The nonequilibrium correction to the distribution function resulting from a temperaturedependent 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 BoseEinstein gases within the ChapmanEnskog and 14moment approaches in the relaxation time approximation. Constant and temperaturedependent 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 temperaturedependent 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 BoseEinstein 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 BoseEinstein statistics.},
doi = {10.1103/PhysRevC.97.044914},
journal = {Physical Review C},
number = 4,
volume = 97,
place = {United States},
year = {2018},
month = {4}
}