Abstract

Flavour-changing transitions of charged leptons have been searched for since the early days of particle physics, helping to shape the basic laws that any successful model should obey. First I will describe the current experimental and theoretical state of the field, and explain why the next generation of experiments could hold the keys to a fuller understanding of our universe, offering discovery potential complementary to the high energy frontier. I will then focus on muon-to-electron conversion experiments, specifically the COMET/PRISM programme which promises a sensitivity improvement of four orders of magnitude compared to the present record, and potentially a six order improvement. Recently the host laboratory has approved COMET Phase-I, and we aim to start data-taking in 2016.