The partonic structure of the generalized BFKL Pomeron (original) (raw)
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Diffractive DIS from the generalized BFKL pomeron. Predictions for HERA
Arxiv preprint hep-ph/ …, 1994
We present a microscopic QCD calculation of the cross section of diractive DIS and of the partonic structure of the pomeron from the dipole approach to the generalized BFKL pomeron. We carry out a detailed analysis of how one can factor out the non perturbative normalization of the diractive DIS cross section and its Q 2 evolution, which can be cast in the form of the conventional QCD evolution. We demonstrate that the pomeron cannot be treated as a particle with a uniquely dened structure function and ux in the proton. We nd a strong factorization breaking which can approximately be described by the two-component structure function of the pomeron, each component endowed with a dierent ux of pomerons in the proton. We predict a very weak Q 2 dependence of the diractive contribution to the proton structure function. *
Probing the structure of the pomeron
The European Physical Journal C, 1999
We suggest that the pseudo-rapidity cut dependence of diffractive deep-inelastic scattering events at HERA may provide a sensitive test of models of diffraction. A comparison with the experimental cross section shows that the Donnachie-Landshoff model and a simple two-gluon exchange model of the pomeron model are disfavoured. However a model with a direct coupling of the pomeron to quarks is viable for a harder quark-pomeron form factor, as is a model based on the leading-twist operator contribution. We also consider a direct-coupling scalar pomeron model. We comment on the implications of these results for the determination of the partonic structure of the pomeron.
The Phenomenology of Pomeron Enhancement
2009
Multi Pomeron interactions are the main source of high mass diffraction. Their role in high energy dynamics greatly influences the predictions for high energy cross sections and survival probabilities of hard diffraction channels, notably, diffractive Higgs production at the LHC. Our approach, is motivated by the fact that we obtain a very small value for the fitted slope of the Pomeron trajectory, which justifies the use of perturbative QCD for soft scattering. Our suggested model differs from the proposal of the Durham KMR group which is based on a parton model interpretation of the Reggeon calculus in the complex J-plane in which multi Pomeron vertices are arbitrarily defined. The theoretical input and predictions of the two groups, as well as their data analysis and procedures are compared and evaluated.
Physics Letters B, 1995
In the framework of anisotropic Chromodynamics, a non-perturbative realization of QCD, we develop the Low-Nussinov picture of the Pomeron. In this approach all the usual problems of low pT perturbative calculations (infrared divergence) are naturally absent. Thus, we are able to perform an ab initio calculation of the hadron-hadron total cross section. The result is a cross section of the same magnitude as indicated experimentally and approximately energy-independent (with a log2s growth). We further discuss the pT dependence of the hadron-hadron elastic-scattering cross section, which displays all the experimentally observed features.
Pomeron Vertices in Perturbative QCD in Diffractive Scattering
2004
We analyse the momentum space triple Pomeron vertex in perturbative QCD. In addition to the standard form of this vertex which is used in the context of total crosssections at high energies and in the QCD reggeon field theory, there exists an alternative form which has to be used in the study of high-mass diffraction. We review and analyse the relation between these two versions. We discuss some implications for the BK-equation. In the second part of our paper we extend this analysis to the Pomeron-Odderon-Odderon vertex.
The two-component non-perturbative pomeron and the G-Universality
Nuclear Physics B - Proceedings Supplements, 2001
In this communication we present a generalization of the Donnachie-Landshoff model inspired by the recent discovery of a 2-component Pomeron in LLA-QCD by Bartels, Lipatov and Vacca. In particular, we explore a new property, not present in the usual Regge theory -the G-Universality -which signifies the independence of one of the Pomeron components on the nature of the initial and final hadrons. The best description of the pp, pp, r*p, K&p, yy and yp forward data is obtained when G-universality is imposed. Moreover, the en's behaviour of the hadron amplitude, first established by Heisenberg, is clearly favoured by the data.
A Light-Front Quark Model for the Electromagnetic Form Factor of the Pion
Theoretical Nuclear Physics in Italy, 2005
In this contribution, an approach for a unified description of the pion electromagnetic form factor, in the space-and time-like regions, within a constituent quark model on the light front, will be reviewed. Our approach is based on i) the onshell quark-hadron vertex functions in the valence sector, ii) the dressed photon vertex where a photon decays in a quark-antiquark pair, and iii) the emission and absorption amplitudes of a pion by a quark. Results favorably compare with the existing experimental data.
Direct calculation of the triple-pomeron coupling for diffractive DIS and real photoproduction
1994
We present a unified direct calculation of the triple-pomeron coupling A3Pom(Q2)A_{3\Pom}(Q^{2})A3Pom(Q2) for diffractive real photoproduction ($Q^{2}=0$) and deep inelastic scattering at large Q2Q^{2}Q2 in the framework of the dipole approach to the generalized BFKL pomeron. The small phenomenological value of A3Pom(0)approx0.16A_{3\Pom}(0)\approx 0.16A3Pom(0)approx0.16\,GeV$^{2}$, which was a mystery, is related to the small correlation radius Rcapprox0.3R_{c}\approx 0.3Rcapprox0.3\,fm for the perturbative gluons. We confirm the early expectations of weak Q2Q^{2}Q2 dependence of the dimensionfull coupling A3Pom(Q2)A_{3\Pom}(Q^{2})A3Pom(Q2) and predict that it rises by the factor sim1.6\sim 1.6sim1.6 from real photoproduction to deep inelastic scattering.