2020 Impact factor 4.590
Particles and Fields
Eur. Phys. J. C 13, 197-212
DOI 10.1007/s100520000272

A study of three-prong tau decays with charged kaons

The OPAL Collaboration

G.Abbiendi$^{\rm 2}$ - et al.

2Dipartimento di Fisica dell' Università di Bologna and INFN, 40126 Bologna, Italy

Received: 9 July 1999 / Published online: 17 February 2000 - © Springer-Verlag 2000

From an analysis of the ionisation energy loss of charged particles selected from a sample of 147926 ${\rm e}^+{\rm e}^- \!\!\rightarrow\!
\tau^+\tau^-$ candidates recorded in the OPAL detector at ${\rm e}^+{\rm e}^-$ centre-of-mass energies near the ${\rm
Z}^0$ resonance, we determine the branching ratios:

\begin{eqnarray*}{\rm Br}(\tau^-\rightarrow \,\nu_\tau\, {\rm K}^-\pi^-\pi^+ (\p...
...{\rm K}^+ (\pi^0))
& = & 0.159\pm0.053\pm0.020 \;\% ,

where the $(\pi^0)$ notation refers to decay modes with or without an accompanying $\pi^0$. The

\begin{displaymath}\tau^- \rightarrow \nu_\tau {\rm K}^-\pi^- \pi^+

final states occurring through $\tau^- \rightarrow
\nu_\tau {\rm K}^-{\rm K}^0_{\rm S} (\pi^0)$are treated as background in this analysis.
We also examine the resonant structure of $\tau^- \!\!\rightarrow\!\!
\,\nu_\tau\, {\rm K}^-\pi^-\pi^+$ candidates. Under the assumption that the resonant structure is dominated by the K1 resonances, we determine:

\begin{eqnarray*}R & = & {{{\rm Br}(\tau^-\rightarrow \,\nu_\tau\, {\rm K}_1(127...
...\tau\, {\rm K}_1(1270))}
= 0.71 \pm 0.16 \pm 0.11 .

In all results, the first uncertainties are statistical and the second are systematic.

Copyright Società Italiana di Fisica, Springer-Verlag 2000