The LSND/MiniBooNe excess events and heavy neutrino from muon and kaon decays

TL;DR

This paper explores the hypothesis that heavy sterile neutrinos could explain excess events in LSND and MiniBooNE experiments, proposing new decay searches in muon and kaon decays to confirm or refute their existence.

Contribution

It introduces a novel experimental approach to search for heavy sterile neutrinos via decay signatures in muon and kaon decays, complementing existing anomaly investigations.

Findings

Bounds on muon mixing strength are consistent with the heavy neutrino hypothesis.

Proposes a new experimental method to detect heavy neutrino decay signatures.

No current experiments specifically search for these decay signatures.

Abstract

It has been recently shown that puzzling excess events observed by the LSND and MiniBooNE neutrino experiments could be interpreted as a signal from the radiative decay of a heavy sterile neutrino ($\nu_h$) of the mass from 40 to 80 MeV, with a muonic mixing strength $\mix \simeq 10^{-3} - 10^{-2}$, and the lifetime $10^{-11} < \tau_h < 10^{-9}$ s. We discuss bounds on $\mix$ obtained from the recent precision measurements with muons and show that they are consistent with the above limits. If the $\nu_h$ exists its admixture in the ordinary muon or kaon decay would result in the decay chain $\muhd$ or $\khd$, respectively. We propose a new experiment for a sensitive search for these processes in $\mu$ and $K$ decays at rest allowing to either definitively confirm or exclude the existence of the $\nu_h$. To our knowledge, no experiment has specifically searched for the signature of radiative decay of massive neutrinos from particles decays as proposed in this work. The search is complementary to the current experimental efforts to clarify the origin of the LSND and MiniBooNE anomalies.