# Studies of tau-> eta.K-.nu and tau-> eta.pi-.nu at BaBar and a search for a second-class current - High Energy Physics - Experiment

Abstract: We report on analyses of tau lepton decays $\tau^- \to \eta K^- u {\tau}$and $\tau^- \to \eta \pi^- u {\tau}$, with $\eta \to \pi^+ \pi^- \pi^0$,using 470 fb$^{-1}$ of data from the Babar experiment at PEP-II, collected atcenter-of-mass energies at and near the $\Upsilon4S$ resonance. We measurethe branching fraction for the $\tau^- \to \eta K^- u {\tau}$ decay mode,$\Br\tau^- \to \eta K^- u {\tau} =1.42\pm0.11\text{stat}\pm0.07\text{syst}\times10^{-4}$, and report a 95%confidence level upper limit for the second-class current process $\tau^- \to\eta \pi^- u {\tau}$, $\Br\tau^- \to \eta \pi^- u {\tau} <9.9\times10^{-5}$.

Author: The BaBar Collaboration, P. del Amo Sanchez, et al

Source: https://arxiv.org/