Shear viscosity of a pion gas due to $\rho \pi \pi$ and $\sigma \pi \pi$ interactions

Abstract

We have calculated the shear viscosity of pion medium, where propagating pion has some finite thermal width due to interaction with the low mass resonances, $\sigma$ and $\rho$. With the help of standard thermal field theoretical technique, the thermal width of the pion has been calculated from the pion self-energy diagram for $\pi \sigma$ and $\pi \rho$ loops, where an effective Lagrangian density has been used for interaction part. We have found a very small value of shear viscosity by entropy density ratio ($\eta /s$), which is very close to the KSS bound.

Comments: Published in Proceedings of Science (Conference : ICPAQGP-2015)