New ideas to improve searches for μ+ → e+γ

Searching for decays that change total lepton family number is an excellent method to explore potential physics beyond the Standard Model because those processes are predicted to be zero except when new physics is present. Essentially all extensions of the Standard Model that introduce new, heavy particles predict the existence of these rare decays, though the most probable channel is highly model dependent. Recently, the prejudice has grown within the physics community that supersymmetry is an extension that is likely to be related to nature. Barbieri, Hall, and Strumia show that rare decays are signatures for grand unified supersymmetry and calculate the rates for μ+ → e+γ and related processes for a wide range of parameters of these models. They conclude that μ+ → e+γ has the largest rate by more than two orders of magnitude, and it ranges between the current experimental limit and 10-14. Hence, there is continuing interest in the community for an experiment that could have a sensitivity near 10-14. Lessons are drawn from the experience of the MEGA experiment in searching for μ+ to e+γ. In light of that experience, some ideas are evaluated regarding new searches that might take place in the ERA of a source of low-energy muons associated with a muon collider