Absorptive effects in exclusive diffraction dissociation

Abstract

We report a detailed investigation of absorptive corrections in Good-Walker and Deck-type models for production of three-body final states in diffraction dissociation processes. Beginning with an input elastic diffractive amplitude which is central in impact parameter, the model generates naturally a peripheral structure for inelastic diffraction. For $\mathrm{pp}\ensuremath{\rightarrow}(n{\ensuremath{\pi}}^{+})p$ and $\mathrm{np}\ensuremath{\rightarrow}(p{\ensuremath{\pi}}^{\ensuremath{-}})p$, at small excitation mass, absorptive effects create significant dip structure in the production momentum transfer distribution $\frac{d\ensuremath{\sigma}}{\mathrm{dt}\mathrm{dM}}$ near $t\ensuremath{\simeq}\ensuremath{-}0.3$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$, in agreement with data from Fermilab and the CERN ISR. Similar behavior is predicted for $\ensuremath{\pi}p\ensuremath{\rightarrow}{A}_{1}p$ and $\mathrm{Kp}\ensuremath{\rightarrow}\mathrm{Qp}$, but at larger $|t|$. Distributions in other kinematic variables are much less affected by absorption. We provide a decomposition of the total $\frac{d\ensuremath{\sigma}}{\mathrm{dt}\mathrm{dM}}$ into partial cross sections for the various angular momentum and helicity states which comprise the low-mass diffractive enhancement. The $s$-wave amplitude is dominant in both absorbed and unabsorbed models. A pronounced mass-slope correlation is present both in the total $\frac{d\ensuremath{\sigma}}{\mathrm{dt}\mathrm{dM}}$ and in the $s$-wave part alone.