Inclusive spectra in single- and double-excitation models

Abstract

The inclusive pion spectra in p-p collisions predicted by the single-excitation (or Nova) model and the double-excitation model are discussed. The description is given in terms of the rapidityy, which facilitates the comparison of the two models. Whereas in the limit of infinite energies the two models may be shown to have the same form, their predictions at accelerator and even at ISR energies differ appreciably. In particular we discuss the question of how the scaling limit in the central region is reached, and which factors in the model govern the approach. The problem of enforcing a cut-off in momentum transfer is examined, and it is found that the effect of such a cut-off is to cause a dip in the central plateau. However the effect is much more severe for the double-excitation model than for the single-excitation one. Furthermore the contribution of the two-fireball model to the inelastic cross-section is found to increase considerably between accelerator and ISR energies, to such an extent that it should be the dominant process at very high energies.