2020 Impact factor 4.590
Particles and Fields
Eur. Phys. J. C 4, 29-45
DOI 10.1007/s100529800879

K0S production in ${\tau}$decays

The ALEPH Collaboration
R. Barate - et al.

Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS, F-74019 Annecy-le-Vieux Cedex, France

Received: 6 January 1998 / Published online: 15 May 1998

Abstract
From a sample of about 160k $\mbox{Z}\!\!\to\!\!\tau^+\tau^-$ candidates collected with the ALEPH detector at LEP between 1991 and 1995, ${\tau}$ lepton decays involving $K^0_S\!\to\!\pi^+\pi^-$are studied. The K0SK0L associated production in ${\tau}$decays is also investigated. The branching ratios are measured for the inclusive decay $B(\tau^-\!\!\to\!\!K^0_SX^-\nu_\tau)=(9.70\!\pm\!0.58\!\pm\!0.62)\times10^{-3}$,where X- can be anything, and for the exclusive decays


\begin{tabular}
{rcl}
$B(\tau^-\!\!\to\!\!\overline{K}^0\pi^-\nu_\tau)$&=&$(8.55...
 ...\pi^0\nu_\tau)$&=&$(1.52\!\pm\!0.76\!
\pm\!0.21)\times10^{-3}$. \\ \end{tabular}
The decay $\tau^-\!\!\to\!\!K^0_SK^0_L\pi^-\nu_\tau$ is studied for the first time, giving a branching ratio

\begin{tabular}
{rcl}
$B(\tau^-\!\!\to\!\!K^0_SK^0_L\pi^-\nu_\tau)$&=&$
(1.01\!\pm\!0.23\!\pm\!0.13)\times10^{-3}.$\end{tabular}
The channels $\tau^-~\!\!\!\to\!\!\!~K^0_SK^0_S\pi^-\nu_\tau~$,$\tau^-~\!\!\!\to\!\!\!~K^0_SK^0_S\pi^-\pi^0\nu_\tau~$,$\tau^-~\!\!\!\to\!\!\!~K^0_SK^0_L\pi^-\pi^0\nu_\tau~$,$\tau^-~\!\!\!\to\!\!\!~\overline{K}^0\pi^-\pi^0\pi^0\nu_\tau$,$\tau^-~\!\!\!\to\!\!\!~K^0K^-\pi^0\pi^0\nu_\tau$ and $\tau^-~\!\!\!\to\!\!\!~K^0h^+h^-h^-\nu_\tau$ are also investigated. In addition, mass spectra in the K0Sh- and $K^0_Sh^-\pi^0$ final states are analysed to provide information on the intermediate states produced in the decays.


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