Measurement of the τ−→h−h+h−vτ and τ−→h−h+h−≥1π0vτ branching ratios

The branching ratios of the τ−→h−h+h−vτ and τ−→h−h+h−≥1π0vτ decays, whereh is either a charged π orK meson, are measured using a data sample of 87861 τ+τ− pairs collected with the OPAL detector at LEP. The two branching ratios are extracted simultaneously from a sample of three charged particle decays and found to be:$$\begin{gathered} B(\tau ^ - \to h^ - h^ + h^ - \nu _\tau ) = (9.87 \pm 0.10 \pm 0.24)\% \hfill \\ B(\tau ^ - \to h^ - h^ + h^ - \geqslant 1\pi ^0 \nu _\tau ) = (5.09 \pm 0.10 \pm 0.23)\% \hfill \\ \end{gathered}$$ where the first error is statistical and the second systematic. The branching ratio of the τ lepton into three charged particles is measured to be:$$B(\tau ^ - \to 3 - prong) = (14.96 \pm 0.09 \pm 0.22)\%$$