Searching for Hidden Neutrons with a Reactor Neutrino Experiment: Constraints from the STEREO Experiment

TL;DR

This paper reports a new experimental constraint on neutron conversion into hidden neutrons using the STEREO reactor neutrino experiment, setting a limit that surpasses previous bounds and demonstrating the potential of neutrino experiments in searching for hidden neutrons.

Contribution

The study provides the first competitive constraint on neutron to hidden neutron conversion probability from a short-baseline neutrino experiment.

Findings

Limit on neutron to hidden neutron conversion probability: p<3.1×10^{-11} at 95% C.L.

Improved previous limit by a factor of 13.

Shows short-baseline neutrino experiments can search for hidden neutrons.

Abstract

Different extensions of the standard model of particle physics, such as braneworld or mirror matter models, predict the existence of a neutron sterile state, possibly as a dark matter candidate. This Letter reports a new experimental constraint on the probability $p$ for neutron conversion into a hidden neutron, set by the STEREO experiment at the high flux reactor of the Institut Laue-Langevin. The limit is $p<3.1\times 10^{-11}$ at $95 \%$ C.L. improving the previous limit by a factor 13. This result demonstrates that short-baseline neutrino experiments can be used as competitive passing-through-walls neutron experiments to search for hidden neutrons.