Effects of CP Violation from Neutral Heavy Fermions on Neutrino Oscillations, and the LSND/MiniBooNE Anomalies

TL;DR

This paper explores how CP violation from heavy neutral fermions influences neutrino oscillations and proposes a model with sterile neutrinos that can explain LSND and MiniBooNE anomalies while remaining consistent with existing experimental constraints.

Contribution

It introduces a simple formula capturing heavy fermion effects on neutrino oscillations with observable CP violation, and demonstrates a sterile neutrino model fitting anomalies and null results.

Findings

A formula with four parameters describes heavy fermion effects on oscillations.

A sterile neutrino model explains LSND and MiniBooNE anomalies.

The model aligns with existing short baseline experimental constraints.

Abstract

Neutrinos may mix with ultralight fermions, which gives flavor oscillations, and with heavier fermions, which yields short distance flavor change. I consider the case where both effects are present. I show that in the limit where a single oscillation length is experimentally accessible, the effects of heavier fermions on neutrino oscillations can generically be accounted for by a simple formula containing four parameters, including observable CP violation. I consider the anomalous LSND and MiniBooNE results, and show that these can be fit in a model with CP violation and two additional sterile neutrinos, one in the mass range between 0.1 and 20 eV, and the other with mass between 33 eV and 40 GeV. I also show that this model can avoid conflict with constraints from existing null short baseline experimental results.