Implications of Improved Upper Bounds on $|\Delta L|=2$ Processes

Abstract

We discuss implications of improved upper bounds on the $|\Delta L|=2$ processes (i) $K^{+}\to {\pi }^{-}{\mu }^{+}{\mu }^{+}$, from an experiment at BNL, and (ii) ${\mu }^{-}\to e^{+}$ 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.

Comments: 8 pages, Latex; published version with figs. added (Phys. Lett. B, in press)