The Flavour of Muons - Searching for Lepton Flavour Violation with the Mu3e Experiment

• Ann-Kathrin Perrevoort

The observation of lepton flavour violation (LFV) in the charged lepton sector would be an unambiguous sign of physics beyond the Standard Model (BSM), and is thus the channel of choice for many BSM searches. LFV searches in muon decays in particular have the benefit that muons can be easily produced at high rates. There is a global effort to search for LFV at high intensity muon sources to which the upcoming Mu3e experiment at the Paul Scherrer Institute (PSI) will contribute. The Mu3e Collaboration aims to perform a background-free search for the LFV decay mu+->e+e−e+ with an unprecedented sensitivity in the order of 10E-15 in the first phase of operation, and 10E-16 in the final phase - an improvement over the preceding SINDRUM experiment by four orders of magnitude. The high muon stopping rates and low momenta of the decay electrons make high demands on momentum and time resolution and the data acquisition. The innovative experimental concept is based on a tracking detector built from novel ultra-thin silicon pixel sensors and scintillating fibres and tiles, as well as realtime online event reconstruction and filtering. The experimental concept including recent developments in the construction of the phase I experiment as well as physics opportunities will be presented.