Download or read book Measurement of the Branching Fraction for $\tau\to\eta K\nu_\tau$ and a Search for Second-class Currents in $\tau\to\eta\pi\nu_\tau$ with $\eta\to\pi ̂\pi-̂\pi0$ written by and published by . This book was released on 2011 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors report on analyses of tau lepton decays?− →?K−?{sub?} and?− →??−?{sub?}, with? →??−?°, using 470 fb−1 of data from the BABAR experiment at PEP-II, collected at center-of-mass energies at and near the?(4S) resonance. They measure the branching fraction for the?− →?K−?{sub?} decay mode,?({tau}− →?K−?{sub {tau}}) = (1.42 ± 0.11(stat) ± 0.07(syst)) x 10−4, and report a 95% confidence level upper limit for the second-class current process {tau}− →??−?{sub {tau}},?({tau}− →??−?{sub {tau}})