π-π Scattering in the boundary-condition model

Abstract

The boundary-condition model is used to generate pionpion amplitudes in theT=0, 2S-states and theT=1P-state. The parameters of the model are restricted by three crossing symmetry conditions at the symmetry point, reducing the number of independent parameters to as few as three. The remaining parameters are used to fit the data available from multi-pion production experiments. Conclusions are obtained with respect to the distribution of Yukawa potentials of range ∼0.5µ−1, and the boundary conditions at a radius⩽0.25µ−1. TheP-state model has a repulsive potential tail and an attractive core. It leads to the asymmetry of the ρ-mass distribution seen in some experiments. Contributions from ω decay are not required. TheT=2S-state results tend toward a hard core with an attractive tail. The model of theT=0S-state interaction can be either a nonresonanting constant boundary condition with tail, or a resonanting pole-type boundary condition.