Proton-Antiproton Annihilations into Two Mesons

Abstract

Proton-antiproton annihilation cross sections into two mesons are calculated assuming that contributions from the diagrams with a single intermediate meson dominate. Unitary symmetry and $\omega -\phi$ mixing together with the total rates and cross sections for annihilation into two pseudoscalar mesons are used to obtain estimates of the derivative coupling constants for the $\rho$ and $Y$ mesons. (The $Y$ meson is the member of the vector octet which is coupled to the hypercharge current.) The model is thus able to account for the annihilation into two pions and into two kaons, but yields results which are generally too large by an order of magnitude for the other two-meson final states of $p\overline{p}$ annihilations. It is pointed out that if the $\omega \rho \pi$ coupling constant, which is estimated from the $3\pi$ width of the $\omega$, were smaller, and if the pseudoscalar meson intermediate states were neglected, then the model would yield a reasonably good description of the experiments.