Pole and Continuum Contributions to Proton-Proton Scattering

Abstract

The $N\overline{N}\ensuremath{\rightarrow}2\ensuremath{\pi}$ $s$ and $p$ wave and $\ensuremath{\omega}$ contributions to proton-proton scattering have been recomputed, using the scheme of Amati, Leader, and Vitale. The previous anomalies in the phase shifts have disappeared. In addition, the $2\ensuremath{\pi}$ $s$-wave contribution of Bowcock, Cottingham, and Luri\'e is shown to be indistinguishable in effect from the exchange of a scalar meson with a mass of about 400 MeV. However, the $2\ensuremath{\pi}$ $d$ and higher wave contributions of Chew, Goldberger, Low, and Nambu cannot be accurately represented by the exchange of scalar mesons. Either (i) the higher wave contributions calculated by Amati, Leader, and Vitale contain numerical errors, or (ii) a different mechanism is needed for the $2\ensuremath{\pi}$ $s$- and $p$-wave contributions, or (iii) the theoretical approximations used are not sufficient.