Single-Particle Exchange Models for the Reactions $\pi p\to \rho p$, $\overline{p}p\to \overline{Y}Y$, and $\mathrm{np}\to \mathrm{pn}$

The predictions of single-particle exchange models for particle reactions at high energies have been shown by several authors to be altered significantly by the effects of the strong absorption from the entrance and exit channels into the generally numerous competing channels. The necessary modifications of the usual single-particle exchange models have been discussed by Sopkovich, Durand and Chiu, and by Gottfried and Jackson. In the present paper, the predictions of the modified models for the reactions ${\pi }^{\pm }p({\pi }^0, \omega ){\rho }^{\pm }p$, $\overline{p}p(K, K^{*})\overline{Y}Y$, and $np(\pi , \rho )pn$ are compared with the results of recent experiments. [We denote by $ab(e, f, \cdots )cd$ the reaction $a+b\to c+d$, assumed to proceed through the exchange of particles $e, f, \cdots$] The effects of the particle spins, including the decay angular distribution of the ${\rho }^{\pm }$ in the first reaction and the two-particle spin correlations in the $\overline{Y}Y$ system in the second, are discussed in detail. The rather striking success of the modified theories for the foregoing reactions suggests strongly that ideas underlying the modifications are correct in principle, if not in detail.