Novel calculation of weak meson-nucleon couplings

Abstract

We investigate parity-violating (pv) meson-nucleon vertices within the framework of a non-linear chiral effective lagrangian which includes pions and the vector mesons ρ and ω. Nucleons emerge as topological solitons. We find a value for the weak pv π N coupling (∼ × 10 −8) which is considerably smaller than the standard quark-model values. The ω-meson-nucleon couplings h 0 ω and h 1 ω are comparable to the quark-model results. The values for the ρ-meson-nucleon couplings h 0 ρ , h 1 ρ and h 2 ρ are somewhat smaller than the best quark model predictions. Furthermore, we find a non-zero and non-negligible value for the coupling constant h′ 1 ρ ( h′ 1 ρ ≈ −2 × 10 −7). We compare our results with available data by using existing nuclear-structure calculations. The strong meson-nucleon vertices entering into these calculations are also predicted by the soliton scenario, with values close to what is derived from phenomenological boson-exchange models of the nucleon-nucleon interaction. The agreement of the soliton-model predictions with the data is satisfactory. We also discuss possible improvements and limitations of our approach.