More on R-parity and lepton-family number violating couplings from muon(ium) conversion, and \tau and ${\pi }^0$ decays

Abstract

We present a new class of constraints to the lepton-family number and R-parity violating couplings from muonium conversion, ${\mu }^{-}+{}_{22}^{48}Ti\to e^{-}+{}_{22}^{48}Ti$, a class of tau decays, $\tau \to l+$ (light meson) with $l=\mu ore$, and $J/\psi$ and ${\pi }^0$ decays into a lepton pair. We find that ${\mu }^{-}+{}_{22}^{48}Ti\to e^{-}+{}_{22}^{48}Ti$ provides one of the strongest constraints along with $\Delta m_K,\Delta m_B$, $\mu \to e\gamma$ and the neutrinoless double $\beta$ decay. Search for these lepton-family number violating (LFNV) decays forbidden in the standard model is clearly warranted in various low-energy experiments such as Tau-Charm Factories and PSI, etc.

Comments: 13 pages, no figures, RevTeX