EVIDENCE FOR EXCHANGE OF RHO AND A2 REGGE TRAJECTORIES IN REACTIONS PI+P-]PIODELTA++, PI+P-]ETA0DELTA++, AND K+P-]K0DELTA++

A study is made of three reactions involving Δ++ production, π+p → πoΔ++π+p → ηoΔ++ and K+p → KoΔ++ which because of t-channel quantum number restrictions allow the exchange of only a few high-lying Regge trajectories. These trajectories are ρ{variant}, A2 and ρ{variant} + A2 respectively. In this respect these Δ production reactions are similar to the 'elastic' reactions π-p → πon, π-p → ηon and K-p → Kon, which have the same Regge exchanges. Effective α plots for the ρ{variant} and A2 trajectories are obtained from the Δ reaction data, which are consistent with those obtained from the 'elastic' reactions. Differential cross sections for corresponding 'elastic' and inelastic reactions are compared and the observation made that similar exchange particles yield similarly shaped differential cross sections. The reactions in which only the ρ{variant} contributes have narrow forward peaks, dips at t → -0.6 and secondary maxima; those with A2 exchanges have much broader distributions; and those with both ρ{variant} and A2 exchanges have forward peaks of intermediate width. The intermediate character of the K reactions is consistent with SU(3), which would predict roughly equal proportions of ρ{variant} and A2 exchange. Exchange degeneracy is also discussed, especially with regard to the remarkable experimental evidence that the decay correlations of the Δ++ appear to be the same in all three reactions. © 1969.