On Nieh-Yan Transport

TL;DR

This paper investigates nondissipative transport phenomena caused by the Nieh-Yan anomaly, deriving new relations for various currents influenced by torsion and spin chemical potential, including in 2D systems.

Contribution

It introduces novel torsional transport effects and derives constitutive relations for currents affected by the Nieh-Yan anomaly, expanding understanding of torsion-induced transport.

Findings

Identification of new torsion-driven transport effects

Derivation of constitutive relations for axial, heat, stress, and spin currents

Analysis of torsional relations in two-dimensional systems

Abstract

We study nondissipative transport induced by the Nieh-Yan anomaly. After computing the torsional terms in the equilibrium partition function using transgression, we find the constitutive relations for the covariant axial-vector, heat, stress, and spin currents. A number of new transport effects are found, driven by background torsion and the spin chemical potential. Torsional constitutive relations in two-dimensional systems are also analyzed.