The next generation of $\mu\ -> e \gamma$ and $\mu\ -> 3e$ CLFV search experiments

TL;DR

This paper discusses future experimental designs to enhance the sensitivity of searches for charged lepton flavor violation in muon decays, focusing on improved detector technologies and higher muon fluxes.

Contribution

It introduces a new detector concept using a silicon pair spectrometer to improve photon energy resolution in $oldsymbol{ ext{μ→eγ}}$ searches and explores designs for next-generation $oldsymbol{ ext{μ→3e}}$ experiments.

Findings

Simulated a new detector design with improved energy resolution.

Analyzed the potential for increased sensitivity with higher muon flux.

Proposed detector configurations for next-generation CLFV searches.

Abstract

We explore the possibilities for extending the sensitivity of current searches for the charged lepton flavor violating decays $\mu\ -> e \gamma$ and $\mu\ -> eee$. A future facility such as Project X at Fermilab could provide a much more intense stopping $\mu^+$ beam, facilitating more sensitive searches, but improved detectors will be required as well. Current searches are limited by accidental and physics backgrounds, as well as by the total number of stopped muons. One of the limiting factors in current detectors for $\mu\ -> e \gamma$ searches is the photon energy resolution of the calorimeter. We present a new fast Monte Carlo simulation of a conceptual design of a new experimental concept that detects converted $e^+e^-$ pairs from signal photons, taking advantage of the improved energy resolution of a pair spectrometer based on a silicon charged particle tracker. We also study a related detector design for a next generation $\mu\to eee$ search experiment.