Flavor violating muon decay into an electron and a light gauge boson

TL;DR

This paper investigates the rare muon decay into an electron and a light gauge boson, analyzing theoretical models and experimental prospects, especially in the ultralight gauge boson regime.

Contribution

It introduces explicit models for muon to electron decay involving a light gauge boson, including effective field theory analysis and phenomenological implications.

Findings

Decay can occur at tree level and one-loop level in proposed models.

Current experimental limits constrain the parameter space of such decays.

Prospects for observing this decay depend on future experimental sensitivities.

Abstract

We analyze the flavor violating muon decay $\mu\rightarrow e\chi$, where $\chi$ is a massive gauge boson, with emphasis in the regime where $\chi$ is ultralight. We first study this process from an effective field theory standpoint in terms of form factors. We then present two explicit models where $\mu\rightarrow e\chi$ is generated at tree level and at the one-loop level. We also comment on the prospects of observing the process $\mu\rightarrow e\chi$ in view of the current limits on $\mu\rightarrow 3e$ from the SINDRUM collaboration.