Interaction of Neutrinos with a Cosmological K-essence Scalar

TL;DR

This paper explores how neutrinos interact with a Lorentz-violating k-essence scalar field, affecting their dispersion and oscillation behavior, and constrains such interactions based on experimental considerations.

Contribution

It introduces a novel coupling mechanism between neutrinos and k-essence fields, deriving the impact on neutrino velocities and oscillation lengths, highlighting Lorentz violation effects.

Findings

Non-diagonal k-essence coupling alters neutrino oscillation length to scale as E^{-1}

Constraints on flavor-changing interactions to align with experimental data

Physical effects depend on the speed of sound differing from light speed

Abstract

In this paper we study a novel means of coupling neutrinos to a Lorentz violating background k-essence field. We first look into the effect that k-essence has on the neutrino dispersion relation and derive a general formula for the neutrino velocity in the presence on a k-essence background. The influence of k-essence coupling on neutrino oscillations is then considered. It is found that a non-diagonal k-essence coupling leads to an oscillation length that goes like \lambda \sim E^{-1} where E is the energy. This should be contrasted with the \lambda \sim E dependence seen in the standard mass-induced mechanism of neutrino oscillations. While such a scenario is not favored experimentally, it places constraints on the interactions of the neutrino with a cosmological k-essence scalar background by requiring it to be flavor diagonal. All non-trivial physical effects discussed here require the speed of sound to be different from the speed of light and hence are primarily a consequence of Lorentz violation.