Quantum reflection of massless neutrinos from a torsion-induced potential

TL;DR

This paper investigates how torsion-induced potentials in Einstein-Cartan-Dirac theory can cause massless neutrinos to reflect, depending on medium polarization and density, revealing potential quantum gravitational effects.

Contribution

It introduces a model for neutrino reflection caused by torsion in spacetime, highlighting conditions for observable effects in high-density fermionic media.

Findings

Reflection amplitude depends on medium polarization.

A fraction of neutrinos reflect under certain conditions.

Observable effects require high fermionic densities.

Abstract

In the context of the Einstein-Cartan-Dirac model, where the torsion of the space-time couples to the axial currents of the fermions, we study the effects of this quantum-gravitational interaction on a massless neutrino beam crossing through a medium with high number density of fermions at rest. We calculate the reflection amplitude and show that a specific fraction of the incident neutrinos reflects from this potential if the polarization of the medium is different from zero. We also discuss the order of magnitude of the fermionic number density in which this phenomenon is observable, in other theoretical contexts, for example the strong-gravity regime and the effective field theory approach.