Light sterile neutrinos: oscillations and cosmology

TL;DR

This paper reviews the current understanding of light sterile neutrinos around 1 eV, focusing on oscillation anomalies, experimental results, and tensions with cosmological data within the 3+1 model.

Contribution

It provides a comprehensive review of experimental searches, analyzes the challenges in combining data, and discusses the tension between neutrino oscillation results and cosmological constraints.

Findings

Preferences for non-zero active-sterile mixing angles from experiments

Inconsistencies among different oscillation experiment results

Tension between neutrino data and cosmological observations

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 review our current knowledge of 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. A short summary on the tension with cosmological observations is also provided.