Nonequilibrium chiral perturbation theory

TL;DR

This paper extends chiral perturbation theory to non-equilibrium conditions using the Schwinger-Keldysh formalism, enabling analysis of pion dynamics with a time-dependent decay constant relevant for heavy-ion collisions.

Contribution

It introduces a non-equilibrium extension of chiral perturbation theory with a novel renormalization approach via curved space-time QFT techniques.

Findings

Time-dependent pion decay constant modeled

Renormalization achieved through curved space-time analogy

Applicability demonstrated for relativistic heavy-ion collisions

Abstract

We explore the extension of chiral perturbation theory out of thermal equilibrium. The pion decay constant becomes then a time-dependent function and we work within the Schwinger-Keldysh contour technique. A useful connection with curved space-time QFT allows to renormalise the model. We discuss the applicability of our approach within a relativistic heavy-ion collision environment.