Spin Precession of Slow Neutrons in Einstein-Cartan Gravity with Torsion, Chameleon and Magnetic Field

TL;DR

This paper investigates how slow neutrons' spins precess in Einstein-Cartan gravity with torsion, chameleon, and magnetic fields, revealing potential origins of CP and T violation and baryon asymmetry in the universe.

Contribution

It derives the low-energy neutron spin dynamics in Einstein-Cartan gravity with torsion, including interactions with magnetic fields, and identifies anti-Hermitian torsion-fermion operators that violate CP and T invariance.

Findings

Anti-Hermitian torsion-fermion operators violate CP and T invariance.

Torsion interactions may contribute to baryon asymmetry.

Neutron spin precession is affected by torsion, chameleon, and magnetic fields.

Abstract

We analyse a spin precession of slow neutrons in the Einstein-Cartan gravity with torsion, chameleon and magnetic field. For the derivation of the Heisenberg equation of motion of the neutron spin we use the effective low-energy potential, derived by Ivanov and Wellenzohn (Phys. Rev. D92, 125004 (2015)) for slow neutrons, coupled to gravitational, chameleon and torsion fields to order 1/m, where m is the neutron mass. In addition to this low-energy interactions we switch on the interaction of slow neutrons with a magnetic field. We show that to linear order approximation with respect to gravitational, chameleon and torsion fields the Dirac Hamilton operator for fermions (neutrons), moving in spacetimes created by rotating coordinate systems, contains the anti-Hermitian operators of torsion-fermion (neutron) interactions, caused by torsion scalar and tensor degrees of freedom. Such anti-Hermitian operators violate CP and T invariance. One may assume that in the rotating Universe and galaxies the obtained anti-Hermitian torsion-fermion interactions might be an origin of i) violation of CP and T invariance in the Universe and ii) of baryon asymmetry.