N̄N annihilation into one meson and meson decay into two or three mesons in the 3P 0 model

Abstract

The coupling constants and the form factor of N̄N annihilation into one meson are calculated in the 3P 0 model. This allows one to estimate the one-meson annihilation potential for the NN system and to give information on the effect of pair creation in the nucleus. The form factor of relative S-wave N̄N coupling to an s-wave meson has a zero at t-value around 5 GeV 2 but the relative D-wave N̄N coupling to a meson decreases slower than that of S-wave and the sign does not change. We study in the same framework the decay of a meson into two or three mesons. The decay widths of ω,ρ, ε, B and A 1 are calculated. The decays of ω, A 1 and virtual π into three π are also studied. We include the final-state interaction by multiplying the amplitude of ππ scattering on the three-meson production amplitudes. The model is tested in the Dalitz-plot distribution of three pions in the decay of A 1 meson production from τ. The selection rules that are obtained from the annihilation model A2, in which a ρ is treated as a qq̄, and from the annihilation model A3, in which a ρ is the two π interacting in the final state are compared, and the experimental data of N N annihilation into mesons and meson decay into mesons are discussed.