Neutrino asymmetry in presence of gravitational interaction

TL;DR

This paper explores how gravitational interactions involving fermion spin in curved space-time can lead to neutrino asymmetry in the universe, especially in asymmetric backgrounds like rotating black holes.

Contribution

It introduces the role of spin-curvature coupling as a CPT-violating term that can generate neutrino asymmetry in asymmetric gravitational fields.

Findings

Gravitational spin-curvature coupling acts as an axial-vector interaction.

Neutrino asymmetry arises in spherically asymmetric space-times.

The effect is significant in rotating black hole and expanding universe models.

Abstract

Propagation of fermions in curved space-time generates a gravitational interaction due to the coupling between spin of the fermion and space-time curvature. This gravitational interaction, which is an axial-vector appears as the CPT violating term in the Lagrangian, can generate the neutrino asymmetry in Universe. If the back-ground metric is spherically asymmetric, say, of rotating black hole, the axisymmetric space-time of an expanding Universe, this interaction as well as the neutrino asymmetry is non-zero.