Measurement of the τ⁻→h ⁻ h ⁺ h ⁻ v _τ and τ⁻→h ⁻ h ⁺ h ⁻≥1π⁰ v _τ branching ratios

Abstract

The branching ratios of the τ⁻→h ⁻ h ⁺ h ⁻ v _τ and τ⁻→h ⁻ h ⁺ h ⁻≥1π⁰ v _τ 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:

$$B(\tau ^ - \to 3 - prong) = (14.96 \pm 0.09 \pm 0.22)\%$$