Implications of Improved Upper Bounds on $|ΔL|=2$ Processes

Abstract

We discuss implications of improved upper bounds on the $|ΔL|=2$ processes (i) $K^+ \to π^- μ^+ μ^+$, from an experiment at BNL, and (ii) $μ^- \to e^+$ conversion, from an experiment at PSI. In particular, we address the issue of constraints on neutrino masses and mixing, and on supersymmetric models with R-parity violation.