Charged Lepton Flavor Violating Experiments with Muons

TL;DR

This paper reviews current and upcoming muon-based experiments searching for charged lepton flavor violation, highlighting their goals, status, and expected sensitivities to detect new physics beyond the Standard Model.

Contribution

It provides a comprehensive overview of the experimental landscape for muon CLFV searches, including recent results and future plans for three key channels.

Findings

MEG II has published initial results from its first year.

Mu3e plans to start data-taking in 2025.

Mu2e and COMET aim to begin in 2026 and 2027, respectively.

Abstract

We report on the status of charged lepton flavor violating (CLFV) experiments with muons. We focus on the three "golden channels": $\mu^{+} \rightarrow e^{+} \gamma$, $\mu^{+} \rightarrow e^{+} e^{-} e^{+}$ and $\mu^{-} N \rightarrow e^{-} N$. The collection of upcoming experiments aim for sensitivity improvements up to $10^{4}$ with respect to previous searches. The MEG II experiment, searching for $\mu^{+} \rightarrow e^{+} \gamma$, is currently in its 4th year of physics data-taking with a published result from its first year of data. The Mu3e experiment is an upcoming experiment searching for $\mu^{+} \rightarrow e^{+} e^{-} e^{+}$ with plans of physics data-taking as soon as 2025. The Mu2e and COMET experiments are upcoming searches for $\mu^{-} N \rightarrow e^{-} N$ with the goal of physics data-taking starting in 2027 and 2026 respectively. This proceeding summarizes the signal signature, expected background, resolutions, and timelines for the mentioned searches.