Longitudinal momentum transfers in the multiperipheral model

Abstract

The inclusion of longitudinal momentum transfers in the multiperipheral model is investigated. As recently pointed out by Jadach and Turnau, these longitudinal momentum transfers, if present, have a very large effect on properties of the model. In this paper we find that data rules out such effects. Furthermore, if the longitudinal momentum effects were present, they would in no way solve the serious problem with the multiperipheral model, that average multiplicity and elastic slope ought to be proportional, but experimentally are not. A multiperipheral model using transverse momentum transfers has fewer phenomenological difficulties than one using total momentum transfer. A powerful constraint on multiparticle models is the requirement that the model simultaneously fit relevant aspects of both multiparticle and elastic data; the elastic scattering is Calculated by unitarity. The multiperipheral model has a serious difficulty with this constraint. In this paper the effect of longitudinal momentum transfers is investigated, and two main conclusions are reached: (i) Longitudinal momentum transfers do not help solve the difficulty. (ii) Multiparticle data rules out using the entire momentum transfer, but is consistent with using only the transverse part, as the main variable on which the amplitude depends. Recently, Jadach and Turnau [1] pointed out a feature of some versions of the multiperipheral model (MPM) which had been overlooked in several recent discussions of the MPM [2-4]. This feature is that the longitudinal momentum transfers provide the transverse momentum cutoff in these versions. In the present paper, this feature isexptored from both theoretical and experimental viewpoints. Several points are to be stressed: the phenomenon described by Jadach and Turnau involves a rapid dependence of average transverse momentum on rapidity gap, which can easily be tested experimentally; it is found that there is almost no effect. Even if there were an effect, the random walk description of the MPM would retain its validity. In particular, some peculiar features of the CLA [5] model are * Research supported in part by the US Atomic Energy Commission.

Stochastic processes and multihadron production

“…The reason for this was pointed out by JADACH and TURNAU [12] namely, that the transversal cutoff in muhiperipheral models is provided by the longitudinal momentum transfer. This results in a strong dependeuce of the cut-off on the rapidity gap size [13].…”

Rapidity and Multiplicity Dependence of Transverse Momentum Spectra in pp Collisions at ISR Energies

“…An alternative explanation comes from a multipheripheral model [15] with a random walk effect in the various exchanges which can generate high-transverse-momentum particles, i.e. the products of an apparent hard scatter.…”