Search for Signatures of Sterile Neutrinos with Double Chooz

TL;DR

This paper reports a search for sterile neutrinos using five years of Double Chooz data, finding no significant evidence for their existence but setting new exclusion limits on their mixing parameters within a specific mass range.

Contribution

The study provides the first constraints on sterile neutrino mixing parameters using the Double Chooz experiment with a two-detector setup over five years.

Findings

No significant sterile neutrino signal detected.

Established exclusion bounds on sterile neutrino mixing angles.

Sensitive to mass-squared differences between 5×10^{-3} and 3×10^{-1} eV^2.

Abstract

We present a search for signatures of neutrino mixing of electron anti-neutrinos with additional hypothetical sterile neutrino flavors using the Double Chooz experiment. The search is based on data from 5 years of operation of Double Chooz, including 2 years in the two-detector configuration. The analysis is based on a profile likelihood, i.e.\ comparing the data to the model prediction of disappearance in a data-to-data comparison of the two respective detectors. The analysis is optimized for a model of three active and one sterile neutrino. It is sensitive in the typical mass range $5 \cdot 10^{-3} $ eV$^2 \lesssim \Delta m^2_{41} \lesssim 3\cdot 10^{-1} $ eV$^2$ for mixing angles down to $\sin^2 2\theta_{14} \gtrsim 0.02$. No significant disappearance additionally to the conventional disappearance related to $\theta_{13} $ is observed and correspondingly exclusion bounds on the sterile mixing parameter $\theta_{14} $ as function of $ \Delta m^2_{41} $ are obtained.