ω, ρ and A2 exchanges in forward two-body amplitudes at high energy

Abstract

The total-cross-section differences and forward differential cross-sections for nondiffractive two-body processes (including the new FNAL data) are analysed and compared with the corresponding Reggepole predictions. The method used is devised to detect possible deviations from these predictions: the data are analysed step by step, independent quantities being fitted separately. All ω amplitudes are found in remarkable agreement with the Regge-pole model, with an intercept\(\alpha _\omega \)=0.44 and residues verifying ω universality. The same is not always true for the isospin-one amplitudes, since difficulties arise in the π\(\pi \)N system for the ρ and in theNN system for the A2. These difficulties might be due to new physical effects. Anyway ρ-A2 exchange degeneracy is strongly violated, at the level of both residues and the intercepts (\(\alpha _\rho \)=0.51, αA2=0.37). The ρ residues are compatible with ρ universality, but there is a 20% breaking of theSU3 prediction for the A2 ones.