Seminarium Kosmologia i Fizyka Cząstek

Many physical situations involve many body systemsthat are far from equilibrium. However, most of techniques weknow for studying out of equilibrium physics can only be usedfor systems close to equilibrium. n-particle irreducible (nPI)effective theories can, in principle, be used to describe systemsthat are arbitrarily far from equilibrium. For example, nPIeffective theories have been used to calculate the long timeevolution of scalar systems, starting from equilibrium initialconditions. The nPI technique has also been used to calculateleading order transport coefficients in gauge theories. Thistalk will give an overview of the basic structure of nPI effectivetheories and the issues of gauge invariance and renormalizability.I will summarize progress that has been made on the calculationof next-to-leading order transport coefficients.