# Improved Constraints on Sterile Neutrinos in the MeV to GeV Mass Range

## TL;DR

This paper provides improved upper bounds on the coupling of sterile neutrinos to electrons across the MeV to GeV mass range by analyzing various nuclear and particle decay data.

## Contribution

It presents new constraints on sterile neutrino couplings using a comprehensive analysis of multiple decay processes, extending the mass range of previous bounds.

## Key findings

- Stronger upper bounds on $|U_{e4}|^2$ across MeV to GeV range.
- Constraints derived from nuclear beta decays and meson decay ratios.
- Enhanced limits improve the parameter space for sterile neutrino models.

## Abstract

Improved upper bounds are presented on the coupling $|U_{e4}|^2$ of an electron to a sterile neutrino $\nu_4$ from analyses of data on nuclear and particle decays, including superallowed nuclear beta decays, the ratios $R^{(\pi)}_{e/\mu}=BR(\pi^+ \to e^+ \nu_e)/BR(\pi^+ \to \mu^+ \nu_\mu)$, $R^{(K)}_{e/\mu}$, $R^{(D_s)}_{e/\tau}$, and $B^+_{e 2}$ decay, covering the mass range from MeV to GeV.