EVIDENCE FOR XI-DEPENDENT AND T-DEPENDENT DAMPING OF THE POMERON FLUXIN THE PROTON

We show that a triple-Regge parametrization of inclusive single diffra ction agrees with the data in the following two domains: (a) xi > 0.03 at all t, (b) \t\ > 1 GeV2 at all xi. Since the triple-Regge parametr ization fails when applied to the full xi-t range of the total single- diffractive cross section, we conclude that damping occurs only at low -xi and low-\t\. We give a (''toy'') parametrization of the damping fa ctor, D(xi), valid at low-\t\, which describes the d sigma(sd)(total)/ dt data at the ISR and roughly accounts for the observed s-dependence of sigma(sd)(total) up to Tevatron energies. However, an effective dam ping factor calculated for the CDF fitted function for d(2)sigma(sd)(t otal)/d xi dt at root s = 1800 GeV and \t\ = 0.05 GeV2, suggests that, at fixed-xi, damping increases as s increases. We conjecture that, in the regions where the triple-Regge formalism describes the data and t here is no evidence of damping, factorization is valid and the Pomeron -flux-factor may be universal. With the assumption that the observed d amping is due to multi-Pomeron exchange, our results imply that the re cent UA8 demonstration that the effective Pomeron trajectory flattens for \t\ > 1 GeV2 is evidence for the onset of the perturbative 2-gluon pomeron. Our damping results may also shed some light on the self-con sistency of recent measurements of hard-diffractive jet production cro ss sections in the UA8, CDF and ZEUS experiments. (C) 1998 Published b y Elsevier Science B.V. All rights reserved.