We compute the transport coefficients, namely, the coefficients of shear and bulk viscosity as well as thermal conductivity for hot and dense quark matter within the Nambu- Jona Lasinio (NJL) model.
The estimation of the transport coefficients is made by
solving the Boltzmann kinetic equation within the relaxation time approximation. The transition rates are calculated
in a manifestly covariant manner to estimate the thermal-averaged cross sections for quark-quark and quark-antiquark scattering.
The calculations are performed for finite chemical potential also. Within the parameters of the model, the
ratio of shear viscosity to entropy density has a minimum at the Mott transition temperature.
At vanishing chemical potential, the ratio of bulk viscosity to entropy density, on the other hand, decreases with temperature with a sharp decrease near the critical temperature, and vanishes beyond it.
The coefficient of thermal conductivity also shows a minimum at the critical temperature.