Evidence for ξ– and t-dependent damping of the Pomeron flux in the proton

We show that a triple-Regge parametrization of inclusive single diffraction agrees with the data in the following two domains: (a) ξ > 0.03 at all t, (b) |t| > 1 GeV2 at all ξ. Since the triple-Regge parametrization fails when applied to the full ξ–t range of the total single-diffractive cross section, we conclude that damping occurs only at low–ξ and low–|t|. We give a (“toy”) parametrization of the damping factor, D(ξ), valid at low-|t|, which describes the dσtotal sd /dt data at the ISR and roughly accounts for the observed s–dependence of σtotal sd up to Tevatron energies. However, an effective damping factor calculated for the CDF fitted function for d2σtotal sd /dξdt at √ s = 1800 GeV and |t| = 0.05 GeV2, suggests that, at fixed-ξ, damping increases as s increases. We conjecture that, in the regions where the triple-Regge formalism describes the data and there is no evidence of damping, factorization is valid and the Pomeronflux-factor may be universal. With the assumption that the observed damping is due to multi-Pomeron exchange, our results imply that the recent 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-consistency of recent measurements of hard-diffractive jet production cross sections in the UA8, CDF and ZEUS experiments. submitted to Physics Letters B ∗ Supported by U.S. National Science Foundation Grant PHY94–23142