Measurement of the spectral function for the $\tau^-\to K^-K_S\nu_{\tau}$ decay

TL;DR

This paper reports a precise measurement of the spectral function and branching fraction for the tau decay into K- K_S neutrino, using a large dataset from the BABAR experiment at 10.6 GeV.

Contribution

The study provides the first detailed spectral function measurement for this decay mode with high statistical precision.

Findings

Branching fraction measured as (0.739 ± 0.011 (stat) ± 0.020 (syst)) × 10^{-3}

Mass spectrum of the K−K_S system obtained

Results agree with previous measurements

Abstract

The decay $\tau^{-}\to K^{-}K_S\nu_{\tau}$ has been studied using $430\times10^6$ $e^+e^-\to \tau^+\tau^-$ events produced at a center-of-mass energy around 10.6 GeV at the PEP-II collider and studied with the BABAR detector. The mass spectrum of the $K^{-}K_S$ system has been measured and the spectral function has been obtained. The measured branching fraction ${\cal B}(\tau^{-}\to K^{-}K_S\nu_{\tau}) = (0.739\pm 0.011(\rm stat.)\pm 0.020(\rm syst.))\times 10^{-3}$ is found to be in agreement with earlier measurements.