Transport phenomena and observables associated with viscous properties of an anisotropic hot QCD medium at finite baryon asymmetry
Abstract
We have studied the shear viscosity, bulk viscosity and associated observables of baryon asymmetric hot QCD medium subjected to weak momentum anisotropy induced by the asymptotic expansion of the medium during the early stages of ultrarelativistic heavy-ion collisions. The shear and bulk viscosities are evaluated by solving the relativistic Boltzmann transport equation within the relaxation time approximation in a kinetic theory framework. We have further analysed the Prandtl number, the Reynolds number, specific shear viscosity, and specific bulk viscosity, characterizing the sound attenuation, flow properties, fluidity, and conformal behavior, respectively. The interactions among the constituent partons are incorporated through the anisotropic quasiparticle distribution functions, with the medium characterized by finite temperature, momentum anisotropy and baryon asymmetry. Our analysis shows that both shear and bulk viscosities decrease with increasing anisotropy in both baryonless and baryon asymmetric media. In contrast, finite baryon asymmetry enhances both viscosities compared with their baryonless counterparts. The effects of expansion-induced anisotropy remain pronounced in both the baryonless and baryon asymmetric media, leading to substantial modifications of the associated viscous observables. These features are attributed primarily to the squeezing of the parton distribution functions caused by expansion-induced momentum anisotropy, together with the resulting modification of the partonic dispersion relations. Our results demonstrate that the expansion-induced anisotropy significantly influences the sound attenuation, flow characteristics, fluidity and conformal behavior of baryon asymmetric hot QCD medium, providing new insights into the viscous properties of the medium created in ultrarelativistic heavy-ion collisions.
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BibTeX
@misc{rath2026transport,
title = {{Transport phenomena and observables associated with viscous properties of an anisotropic hot QCD medium at finite baryon asymmetry}},
author = {Shubhalaxmi Rath and Nicolás A. Neill},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.18581},
eprint = {2607.18581},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.18581},
}
RIS
TY - UNPB
TI - Transport phenomena and observables associated with viscous properties of an anisotropic hot QCD medium at finite baryon asymmetry
AU - Shubhalaxmi Rath
AU - Nicolás A. Neill
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2607.18581
UR - https://arxiv.org/abs/2607.18581
AB - We have studied the shear viscosity, bulk viscosity and associated observables of baryon asymmetric hot QCD medium subjected to weak momentum anisotropy induced by the asymptotic expansion of the medium during the early stages of ultrarelativistic heavy-ion collisions. The shear and bulk viscosities are evaluated by solving the relativistic Boltzmann transport equation within the relaxation time approximation in a kinetic theory framework. We have further analysed the Prandtl number, the Reynolds number, specific shear viscosity, and specific bulk viscosity, characterizing the sound attenuation, flow properties, fluidity, and conformal behavior, respectively. The interactions among the constituent partons are incorporated through the anisotropic quasiparticle distribution functions, with the medium characterized by finite temperature, momentum anisotropy and baryon asymmetry. Our analysis shows that both shear and bulk viscosities decrease with increasing anisotropy in both baryonless and baryon asymmetric media. In contrast, finite baryon asymmetry enhances both viscosities compared with their baryonless counterparts. The effects of expansion-induced anisotropy remain pronounced in both the baryonless and baryon asymmetric media, leading to substantial modifications of the associated viscous observables. These features are attributed primarily to the squeezing of the parton distribution functions caused by expansion-induced momentum anisotropy, together with the resulting modification of the partonic dispersion relations. Our results demonstrate that the expansion-induced anisotropy significantly influences the sound attenuation, flow characteristics, fluidity and conformal behavior of baryon asymmetric hot QCD medium, providing new insights into the viscous properties of the medium created in ultrarelativistic heavy-ion collisions.
ER -