Hard-Pion Calculation ofπ−πScattering

Abstract

A mass-shell current-algebra calculation of $\pi -\pi$ scattering is given. The Weinberg scattering lengths and effective ranges are shown to be valid within a few percent. At the $K$ meson mass, we find the essentially model-independent result ${\delta }^0-{\delta }^2\simeq 35°$. The existing data at higher energies (up to 1 GeV) can be fitted by adjusting a model-dependent parameter.