Bulk viscosity of strange quark matter in an enhanced perturbative QCD model

The bulk viscosity is studied in a thermodynamically enhanced perturbative QCD (EPQ) model that includes the running of both the strong coupling and the strange quark mass. Similar to the results in other effective models, the bulk viscosity in the EPQ model is larger by 1--2 orders of magnitude compared with that in the MIT bag model. Comparison among the different models indicates that the similarity in orders is mainly due to the inclusion of interactions between quarks. When the temperature is relatively low and enters the equation of state of quark matter, the bulk viscosity can be enormously enlarged. For the analytical expression of bulk viscosity, a reasonable range of model parameters is found. Moreover, due to the enlarged bulk viscosity, the damping time of a strange star with about 2 times the solar mass can be as short as ${10}^{\ensuremath{-}3}$ second, showing that massive quark stars could reach stability quickly after some radial unstable activities.