Search for Majoron at the COMET Experiment

TL;DR

This paper explores the potential to detect Majorons, hypothetical particles linked to neutrino mass, at the COMET experiment by expanding search regions and analyzing sensitivities in different phases.

Contribution

It introduces a novel approach to search for Majorons at muon conversion experiments by expanding the signal region and applying likelihood analysis.

Findings

Sensitivity of $ ext{BR}( ext{mu} ightarrow eJ)$ reaches 2.3×10⁻⁵ in Phase-I

Sensitivity improves to about 10⁻⁸ in Phase-II

Future experiments could further enhance Majoron detection prospects

Abstract

A new Goldstone particle named Majoron is introduced in order to explain the origin of neutrino mass by some new physics models assuming that neutrinos are Majorana particle. By expanding signal region and using likelihood analysis, it becomes possible to search for Majoron at experiments that is originally designed to search for $\mu-e$ conversion. For the COMET experiment, the sensitivity of process $\mu \rightarrow eJ$ is able to reach ${\mathcal{B}}(\mu \rightarrow eJ)=2.3\times 10^{-5}$ in Phase-I and $O(10^{-8})$ in Phase-II. Meanwhile, the sensitivities to search for Majoron at future experiments are also discussed in this article.