Originally thought as clean processes to study the hadronization of
the weak currents, semileptonic tau lepton decays can be useful to set
constraints on non-standard (NS) weak interactions. We study the effects
of new interactions in \tau^- \to (\pi^-\eta,\pi^-\pi^0)\nu_{\tau}τ−→(π−η,π−π0)ντ
decays and find that they are sensitive probes of these New Physics
effects in the form of scalar and tensor interactions, respectively.
Further improved measurements at Belle II will set limits on these
scalar interactions that are similar to other low and high energy
processes.
New Physics search in rare $\tau$ decays at Belle and prospects at Belle II
