Renormalization of Composite Operators in time-dependent Backgrounds

Abstract

We study the phenomenon of composite operator renormalization and mixing in systems where time-translational invariance is broken and the evolution is out-of-equilibrium. We show that composite operators mix also through non-local memory terms which persist for periods whose duration is set by the mass scales in the problem.

Comments: 17 pages, 2 figures. Minor corrections to match published version