Nonequilibrium chiral fluid dynamics including dissipation and noise

TL;DR

This paper develops a theoretical framework combining nonequilibrium chiral fluid dynamics with dissipation and noise, using the linear sigma model and 2PI formalism to describe sigma field and quark fluid interactions.

Contribution

It introduces a consistent approach to include dissipation and noise in chiral fluid dynamics via the influence functional and 2PI formalism, enabling self-consistent dynamics and energy conservation.

Findings

Derived Langevin equation for sigma field with explicit damping and noise terms

Formulated a conserved energy-momentum tensor for the coupled system

Analyzed approximations affecting energy balance in the model

Abstract

We present a consistent theoretical approach for the study of nonequilibrium effects in chiral fluid dynamics within the framework of the linear sigma model with constituent quarks. Treating the quarks as an equilibrated heat bath we use the influence functional formalism to obtain a Langevin equation for the sigma field. This allows us to calculate the explicit form of the damping coefficient and the noise correlators. For a selfconsistent derivation of both the dynamics of the sigma field and the quark fluid we have to employ the 2PI (two-particle irreducible) effective action formalism. The energy dissipation from the field to the fluid is treated in the exact formalism of the 2PI effective action where a conserved energy-momentum tensor can be constructed. We derive its form and comment on approximations generating additional terms in the energy-momentum balance of the entire system.