Determination of theτ+Branching Ratio

The branching ratio for the ${\tau }^{+}$ decay mode ($K^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}$) has been obtained from 2332 ${\tau }^{+}$ decays in a bubble chamber containing ${\mathrm{C}}_3$ ${\mathrm{F}}_8$. We find that (5.54±0.12)% of all $K^{+}$ decay by this mode. Combining this result with four previous measurements gives a weighted "world mean" of (5.46±0.09)%.