Quasiparticle hydrodynamics with momentum-dependent relaxation time

We formulate the relativistic dissipative hydrodynamics of a system of quasiparticles from the Boltzmann equation within the ambit of relaxation time approximation with modified collision kernels. We focus on two specific scenarios with single quasiparticle species, (i) the extended relaxation time approximation, and (ii) the novel relaxation time approximation. We find that both approaches lead to equivalent results up to first order in spacetime gradients. We generalize the extended relaxation time approach to incorporate multiple quasiparticle species and obtain the corresponding expressions for the shear (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>η</a:mi><a:mi>s</a:mi></a:msub></a:math>) and bulk (<c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msub><c:mi>ζ</c:mi><c:mi>s</c:mi></c:msub></c:math>) viscous coefficients. As an application, we study the temperature dependence of the transport coefficients of hot QCD medium with quasigluon and (light and strange) quasiquark sectors considering the power law ansatz for the momentum dependence of the relaxation time. We explore the impact of the power law exponent on the ratio <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>ζ</e:mi><e:mi>s</e:mi></e:msub><e:mo>/</e:mo><e:msub><e:mi>η</e:mi><e:mi>s</e:mi></e:msub></e:math>. Our study suggests that in comparison to a constant exponent, a temperature dependent exponent in the power law ansatz is more suitable for modeling the quasiparticle dynamics in the relevant temperature regime of heavy ion collision.