Running coupling constant from lattice data and bulk viscosity of strange quark matter

We study the bulk viscosity of strange quark matter (SQM) in a quasiparticle model at finite chemical potential by extrapolating the previous quasiparticle model of finite temperature lattice QCD. The more proper bulk viscosity coefficient can be given in this model where chemical potential $\mu$ and coupling constant $\emph{g}$ are interdependent. We also apply our result to determine the critical rotation of strange stars by r-mode instability window. Our model is compatible to the millisecond pulsar data for a wide range of mass and radius of the stars.