Observations of Radiativeτ+Decays

Seven examples of the decay mode $K^{+}\to {\pi }^{+}+{\pi }^{+}+{\pi }^{-}+\gamma$ have been found in a systematic study of 3618 ${\tau }^{+}$ decays in nuclear emulsion. The $\gamma$ energies are 6.3±1.5, 11.4±1.4, 13.4±1.4, 14.2±1.4, 17.8±1.3, 27.5±1.0, and 34.0±0.9 MeV. The experimental branching ratio for $\gamma$ energies greater than 11 MeV is $\frac{P(3\mathrm{}\pi +\gamma )}{P\left(3\mathrm{}\pi \right)}=(1.7\mathrm{}\pm 0.7)\times {10}^{-3\mathrm{}}$.