Status and prospects of charged lepton flavor violation searches with the MEG-II experiment

Abstract

The MEG experiment took data at the Paul Scherrer Institut (PSI) in the years 2009-2013 and published the most stringent limit on the charged lepton flavor violating decay µ → eγ: BR(µ → eγ) < 4.2 × 10 −13 @90% C.L. The MEG detector is currently being upgraded in order to reach a sensitivity of ∼ 4 × 10 −14 , which corresponds to an improvement of one order of magnitude. The basic idea of MEG-II is to achieve the highest possible sensitivity by making the maximum use (7 × 10 7 muons/s) of the available muon intensity at PSI with an improved detector, keeping the background at a manageable level. The status of the MEG-II detector and the current schedule will be presented. MEG-II, together with the next generation charged lepton flavor violation experiments Mu3e (µ + → e + e − e + ) at PSI and Mu2e and COMET (µ → e conversion) at Fermilab and J-PARC respectively, will reach very high sensitivities in the next years. Accelerator upgrades are expected that will make muon beams with intensities of the order of 10 10 muons/s feasible. At this extremely high beam rates, new detector concepts should be adopted in order to overcome the accidental background. Some future directions will be discussed.

The search for Lepton-Flavour Violation with the Mu3e Experiment

“…In addition, modern proton accelerator facilities provide a high yield of muons as a secondary beam. The Mu3e experiment is part of ongoing global effort searching for CLFV in muon decays [1,2,3,4,5], aiming for a single event sensitivity of 2 · 10 −15 on the process µ + → e + e + e − , an improvement of 3 orders of magnitude over the SINDRUM result [6].…”