Probing Lepton-number/flavour-violation in Semileptonic Tau Decays into Two Mesons

Abstract

The evaluation, systematic analysis and numerical study of the semileptonic $\tau$-lepton decays with two mesons in the final state has been made in the frame of the standard model extended by right handed neutrinos. In the analysis, heavy-neutrino nondecoupling effects, finite quark masses, quark and meson mixings, finite widths of vector mesons, chiral symmetry breakings in vector-meson--pseudoscalar-meson vertices and effective Higgs-boson--pseudoscalar-meson couplings have been included. Numerical estimates reveal that the decays ${\tau }^{-}\to e^{-}{\pi }^{-}{\pi }^{+}$, ${\tau }^{-}\to e^{-}{K}^{-}{K}^{+}$ and ${\tau }^{-}\to e^{-}{K}^0{\bar{K}}^0$ have branching ratios of the order of $10^{-6}$, close to present-day experimental sensitivities.

Comments: 33 pages, LaTeX, 6 Postscript figures. To appearin Phys. Rev. D