Revisiting quantum decoherence for neutrino oscillations in constant matter density

TL;DR

This paper revisits neutrino oscillation probabilities in matter by incorporating decoherence effects, providing an analytical formula and exploring how decoherence influences oscillation amplitudes and CP asymmetry.

Contribution

It develops an analytical formula for three-generation neutrino oscillations with decoherence in matter, clarifies the interpretation of the decoherence matrix, and explores its effects on oscillation amplitudes and CP violation.

Findings

Decoherence increases oscillation amplitudes independently of energy.

Decoherence reduces the CP asymmetry magnitude.

A degeneracy exists between decoherence parameter and CP phase.

Abstract

We re-examine the matter neutrino oscillation probabilities considering the decoherence phenomenon as a sub-leading effect. In this paper we point out the relevance of having the correct interpretation of the decoherence matrix in the different quantum bases, within the framework of neutrino oscillation probabilities in matter. Based on this treatment we develop an analytical formula for matter neutrino oscillation probabilities for three generations, with a range of application up to the decoherence parameter $\Gamma \sim 10^{-23}$ GeV. We observe that, due to decoherence, the amplitudes of the neutrino/antineutrino oscillation probabilities increase in an energy independent way. We also find that decoherence can reduce the absolute value of the CP asymmetry, relative to its value at the pure oscillation case. As a side effect we have found a degeneracy between the decoherence parameter $\Gamma$ and the CP violation phase $\delta$.