Searching for cLFV with the Mu3e experiment

Abstract

The Mu3e experiment at the Paul-Scherrer-Institut (PSI) searches for the charged lepton flavour violating decay 𝜇 + → 𝑒 + 𝑒 − 𝑒 + . This decay mode is extremely suppressed in the Standard Model, such that any observation would be a clear signature for new physics being at play. The experiment will be conducted in two phases. In Phase I, a single event sensitivity of 2 × 10 −15 is projected to be reached using the Compact Muon Beamline present at PSI. To reach the ultimate sensitivity of 10 −16 in Phase II, an upgrade of the detector as well as a higher intensity muon beamline will be required.The detector system has to provide excellent tracking efficiency as well as momentum, vertex and time resolutions to reach the experimental goals. An unprecedentedly thin silicon pixel tracking detector is being constructed using HV-MAPS, ultra-light services and a gaseous helium cooling system. It is complemented by timing detectors consisting of scintillating fibres and tiles. The full detector is placed inside a solenoidal magnetic field of 1 T. A first run integrating several subdetector prototypes was successfully conducted at PSI in 2021. A second run using cosmic muons took place in the first half of 2022. While the design of the final detector components is being completed, the Mu3e experiment is entering the production stage. Commissioning of the final Phase I detector is planned to start in 2023. In this publication, the status of the Mu3e experiment is presented.

Search for R-Parity-Violation-Induced Charged Lepton Flavor Violation at Future Lepton Colliders

“…For the reasons above, the search for CLFV has attracted great interest in recent decades. Numerous experiments have been performed or will be constructed with different approaches, including muon-based experiments, such as µ − N → e − N at Mu2e [13,14] and COMET [15], µ → eγ at MEG-II [16,17], µ → eee at Mu3e [18,19], and high energy colliders like LEP and LHC looking for CLFV decays of mesons [20][21][22][23], µ, τ [24], Z bosons [25][26][27], and Higgs bosons [28][29][30]. In the next decades, several proposed lepton colliders, such as the Circular Electron Positron Collider (CEPC) [31], the Future Circular Collider (FCC)-ee [32], the International Linear Collider (ILC) [33], the Compact Linear Collider (CLIC) [34] and the Muon Collider [35], will be ideal facilities to further probe CLFV processes [36][37][38][39][40] since they have cleaner environments with low backgrounds and higher luminosity than hadron colliders.…”

A comparative study of Z′ mediated charged lepton flavor violation at future lepton colliders

“…The search for CLFV has attracted long standing interest since it has great potential to probe new physics indirectly at energy scales much higher than what is going to be accessible by the colliders in the foreseeable future. Various searches have been performed at several different approaches [4], including the muon-based experiments (such as µ → eγ at MEG-II [5,6], µ → eee at Mu3e [7,8] and µ − N → e − N at Mu2e [9] and COMET [10]),…”

A Comparative Study of Z$^{\prime}$ mediated Charged Lepton Flavor Violation at future lepton colliders

“…The search for CLFV has attracted long standing interest since it has great potential to probe new physics indirectly at energy scales much higher than what is going to be accessible by the colliders in the foreseeable future. Various searches have been performed at several different approaches [4], including the muon-based experiments (such as µ → eγ at MEG-II [5,6], µ → eee at Mu3e [7,8] and µ − N → e − N at Mu2e [9] and COMET [10]), B factories, and high energy colliders such as LEP and LHC, targeting at the CLFV decays of meson [11][12][13][14], µ, τ , Z [15][16][17] and Higgs boson [18][19][20].…”