Majorana Phase And Matter Effects In Neutrino Chiral Oscillation

TL;DR

This paper investigates how Majorana phases and matter effects influence chiral oscillations of neutrinos, revealing new resonant behaviors and the significance of these effects for non-relativistic neutrinos.

Contribution

It introduces the impact of Majorana phases on neutrino chiral oscillations and identifies a novel matter-induced resonance effect beyond the standard MSW phenomenon.

Findings

Chiral oscillation probability is suppressed for relativistic neutrinos but significant for non-relativistic ones.

Matter modifies neutrino eigen-energies based on helicity, leading to new resonant effects.

Majorana phases affect chiral oscillation behavior in matter.

Abstract

Due to finite masses and mixing, for neutrinos propagation in space-time, there is a chiral oscillation between left- and right- chiral neutrinos, besides the usual oscillation between different generations. The probability of chiral oscillation is suppressed by a factor of $m^2/E^2$ making the effect small for relativistic neutrinos. However, for non-relativistic neutrinos, this effect can be significant. In matter, the equation of motion is modified. When neutrinos produced in weak interaction pass through the matter, the eigen-energies are split into two different ones depending on the helicity of the neutrino. This results in different oscillation behavior for neutrinos with different helicity, in particular there is a new resonant effect related to the helicity state of neutrino different than the usual MSW effect. For Majorana neutrinos, chiral oscillation also depends on Majorana phases.