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 $\mu \rightarrow e \gamma$: BR($\mu \rightarrow e \gamma$) $<4.2 \times 10^{-13}$ $@90\%$ C.L. The MEG detector is currently being upgraded in order to reach a sensitivity of $\sim 4 \times 10^{-14}$, 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 ($7\times10^{7}$ 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 ($\mu^+\rightarrow e^+e^-e^+$) at PSI and Mu2e and COMET ($\mu \rightarrow e$ 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.