Search for a light sterile neutrino with 7.5 years of IceCube DeepCore data

TL;DR

This study searches for eV-scale sterile neutrinos using 7.5 years of IceCube DeepCore data, finding no evidence of mixing and setting new constraints on sterile neutrino parameters, thus contributing to the ongoing debate in neutrino physics.

Contribution

First analysis using extensive IceCube data with improved methods to constrain sterile neutrino mixing parameters at eV scale.

Findings

No evidence of active-sterile neutrino mixing.

Placed new upper limits on mixing matrix elements.

Results increase tension with anomalous appearance signals.

Abstract

We present a search for an eV-scale sterile neutrino using 7.5 years of data from the IceCube DeepCore detector. The analysis uses a sample of 21,914 events with energies between 5 and 150 GeV to search for sterile neutrinos through atmospheric muon neutrino disappearance. Improvements in event selection and treatment of systematic uncertainties provide greater statistical power compared to previous DeepCore sterile neutrino searches. Our results are compatible with the absence of mixing between active and sterile neutrino states, and we place constraints on the mixing matrix elements $|U_{\mu 4}|^2 < 0.0534$ and $|U_{\tau 4}|^2 < 0.0574$ at 90% CL under the assumption that $\Delta m^2_{41}\geq 1\;\mathrm{eV^2}$. These null results add to the growing tension between anomalous appearance results and constraints from disappearance searches in the 3+1 sterile neutrino landscape.