Bulk viscosity of a hot QCD medium in a strong magnetic field within the relaxation-time approximation

The bulk viscosity of hot QCD medium has been obtained in the presence of strong magnetic field. The present investigation involves the estimation of the quark damping rate and subsequently the thermal relaxation time for quarks in the presence of magnetic field while realizing the hot QCD medium as an effective Grand-canonical ensemble of effective gluons and quarks antiquarks. The dominant process in the strong field limit is 1 -> 2 (g -> q (q) over bar), which contributes to the bulk viscosity in the most significant way. Further, setting up the linearized transport equation in the framework of an effective kinetic theory with hot QCD medium effects and employing the relaxation time approximation, the bulk viscosity has been estimated in lowest Landau level and beyond. The temperature dependence of the ratio of the bulk viscosity to entropy density indicates its rising behavior near the transition temperature.