Lepton Flavor Violating $\tau$ Decays in Two Higgs Doublet Model III

Abstract

We study the lepton flavor violating processes of $\tau^-\to\mu^-PP$ decays with $PP=K^+K^-,K^0\bar{K}^0,\pi^+\pi^-,\pi^0\pi^0$ in the framework of two Higgs doublet model III by virtue of the Chiral Perturbation Theory. In this model, only three neutral Higgs bosons contribute to these decays. With the current experimental constraints, we show that (a) the contributions of $|\lambda_{uu(dd)}|$ term are very small for these four decays; (b) we get the correlation between $|\lambda_{ss}|$ and $|\lambda_{\tau\mu}|$. For $|\lambda_{\tau\mu}| \sim 10-400$, one has $|\lambda_{ss}|\sim 40-1$; (c) in the existing model parameter space, $Br(\tau^- \to \mu^- K^+K^-)$ could reach the order of ${\cal O}(10^{-8})$, but $Br(\tau \to \mu^- \pi^+\pi^-/\pi^0\pi^0)$ are too small to be observed.