Atmospheric neutrinos, $nu_e-nu_s$ oscillations, and a novel neutrino evolution equation

TL;DR

This paper explores how atmospheric electron neutrino oscillations involving a sterile neutrino can be accurately modeled using a novel inhomogeneous Schrödinger-like equation, simplifying the complex 3+1 neutrino oscillation scheme.

Contribution

It introduces a new inhomogeneous evolution equation for neutrino flavor transitions, providing a simplified yet accurate description of atmospheric nu_e oscillations with sterile neutrinos.

Findings

Resonance enhancement of nu_e-nu_s oscillations at TeV energies.

Atmospheric nu_e flavor transitions can be modeled with a 2-flavour framework.

Introduction of a novel inhomogeneous Schrödinger-like evolution equation.

Abstract

If a sterile neutrino nu_s with an eV-scale mass and a sizeable mixing to the electron neutrino exists, as indicated by the reactor and gallium neutrino anomalies, a strong resonance enhancement of nu_e-nu_s oscillations of atmospheric neutrinos should occur in the TeV energy range. At these energies neutrino flavour transitions in the 3+1 scheme depend on just one neutrino mass squared difference and are fully described within a 3-flavour oscillation framework. We demonstrate that the flavour transitions of atmospheric nu_e can actually be very accurately described in a 2-flavour framework, with neutrino flavour evolution governed by an inhomogeneous Schroedinger-like equation. Evolution equations of this type have not been previously considered in the theory of neutrino oscillations.