Pion-Pion Interaction inτ+-Meson Decay

Abstract

The deviations of the ${\pi }^{-}$ spectrum in ${\tau }^{+}$-meson decay from the Dalitz-Fabri distribution in the $0^{-}$ state are analyzed on the assumption of a ${\pi }^{+}-{\pi }^{+}$ short-range interaction. Agreement with experiment is found if the absolute value of the ${\pi }^{+}-{\pi }^{+}$ scattering length $\mathrm{}\left|a\right|\mathrm{}$ is 1.4×${10}^{-13\mathrm{}}$ cm. The ${\pi }^{+}$ spectrum is also calculated on the basis of this scattering length and is found to agree with the experimental results.