Transport coefficients in Chiral Perturbation Theory
Departamentos de Fısica Teórica I y II, Universidad Complutense, 28040, Madrid, Spain
Accepted: 15 October 2006
Published online: 22 February 2007
We present recent results on the calculation of transport coefficients for a pion gas at zero chemical potential in Chiral Perturbation Theory (ChPT) using the Linear Response Theory (LRT). More precisely, we show the behavior of DC conductivity and shear viscosity at low temperatures. To compute transport coefficients, the standard power counting of ChPT has to be modified. The effects derived from imposing unitarity are also analyzed. As physical applications in relativistic heavy-ion collisions, we show the relation of the DC conductivity to soft-photon production and phenomenological effects related to a non-zero shear viscosity. In addition, our values for the shear viscosity to entropy ratio satisfy the KSS bound.
PACS: 11.10.Wx Finite-temperature field theory – / 12.39.Fe Chiral Lagrangians – / 25.75.-q Relativistic heavy-ion collisions –
© Società Italiana di Fisica and Springer-Verlag, 2007