Spin-torsion coupling and gravitational moments of Dirac fermions: theory and experimental bounds

TL;DR

This paper investigates the quantum behavior of Dirac fermions in gravitational fields, exploring their gravitational moments, deriving a general transformation, and setting experimental bounds on spacetime torsion.

Contribution

It provides a comprehensive theoretical framework for Dirac fermions in gauge gravitational fields and derives new bounds on spacetime torsion from experimental data.

Findings

Anomalous gravitomagnetic and gravitoelectric moments are excluded.

Derived a general Foldy-Wouthuysen transformation for arbitrary gravitational fields.

Established experimental bounds on spacetime torsion.

Abstract

We discuss the quantum dynamics of the Dirac fermion particle in a gauge gravitational field. The minimal as well as the Pauli-type nonminimal coupling of a fermion with external fields is studied, bringing into consideration the notions of the translational and the Lorentz gravitational moments. The anomalous gravitomagnetic and gravitoelectric moments are ruled out on the basis of the covariance arguments. We derive the general Foldy-Wouthuysen transformation for an arbitrary configuration of the gauge gravitational field without assuming it weak. Making use of the Foldy-Wouthuysen Hamiltonian for the Dirac particle coupled to magnetic field in a noninertial reference system, we analyze the recent experimental data and obtain bounds on the spacetime torsion.