%0 Journal Article
%T Cool Pions move at less than the speed of light
%A Robert D. Pisarski
%A Michel Tytgat
%J Physics
%D 1996
%I arXiv
%X At nonzero temperature, pions propagate through a thermal medium at less than the speed of light. About low temperature, this effect begins not at $\sim T^2$, but at next to leading order, $\sim T^4$. We also derive the generalization of the relation of Gell-Mann, Oakes, and Renner to nonzero temperature.
%U http://arxiv.org/abs/hep-ph/9606459v1