An entropy current in superspace

TL;DR

This paper develops a supersymmetric formulation of an entropy current within the Schwinger-Keldysh framework, providing a quantum definition that respects superspace conservation laws while exhibiting non-conservation in real space.

Contribution

It introduces a novel superspace-based entropy current construction in quantum field theory, extending classical concepts to quantum and supersymmetric regimes.

Findings

Entropy current is conserved in superspace but not in real space.

The formulation is valid in the probe limit, capturing quantum fluctuations.

Provides a quantum mechanical definition of entropy current via external coupling.

Abstract

We construct an entropy current using a supersymmetric formulation of the low-energy effective action for the Schwinger-Keldysh generating functional. We define an entropy current quantum mechanically by coupling it to an external source. It is given by the bottom component of an entropy current superfield which is conserved in superspace, but when restricted to real space satisfies a non-conservation law. Our analysis is valid in the probe limit which allows us to fully treat quantum fluctuations.