Meson-baryon dynamics in the nucleon-antinucleon system. II. Annihilation into two mesons

The annihilation of the nucleon-antinucleon (NN¯) system into two mesons including π, η, η’, ρ, ω, δ, ${\mathrm{a}}_1$, ${\mathrm{a}}_2$, ${\mathrm{f}}_2$ as well as K and ${\mathit{K}}^{\mathrm{*}}$ is studied in a distorted-wave Born-approximation approach, in the conventional framework based on nucleon, delta-isobar, and hyperon (Λ,Σ,${\mathit{Y}}^{\mathrm{*}}$) exchange. Results for branching ratios are in fair agreement with the data; they show a strong sensitivity to the kind of initial-state interaction used. For polarizations and backward differential cross-section data of pp¯→${\mathrm{\pi }}^{+}$ ${\mathrm{\pi }}^{\mathrm{-}}$,${\mathit{K}}^{+}$ ${\mathit{K}}^{\mathrm{-}}$, there are characteristic discrepancies between experiment and model predictions; possible reasons are discussed.