Light sterile neutrinos: the current picture from neutrino oscillations

TL;DR

This paper reviews the current understanding of light sterile neutrinos around 1 eV, focusing on experimental evidence, mixing parameters, and challenges in combining diverse data in the 3+1 model.

Contribution

It provides a comprehensive review of experimental searches and discusses the difficulties in global fits of active-sterile neutrino mixing data.

Findings

Recent experiments show hints of non-zero active-sterile mixing angles.

There are inconsistencies among different experimental results.

Global fits face challenges due to conflicting data.

Abstract

Light sterile neutrinos with a mass around 1 eV have been studied for many years as a possible explanation of the so called short-baseline neutrino oscillation anomalies. Recently, several neutrino oscillation experiments reported preferences for non-zero values of the mixing angles and squared mass differences for active-sterile mixing, which however are not always in agreement. I will review our current knowledge on the light sterile neutrino in the 3+1 model, starting with a separate discussion on the status of the most relevant searches and then analyzing the problems that arise when combining different probes in a global fit.