Triple Pomeron vertex, duality and diffraction dissociation (original) (raw)
Duality and Diffraction Dissociation
Physical Review D, 1973
We discuss diffraction dissociation in the context of a dual model. We show how direct• channel resonances in the pomeron-particle amplitude build the pomeron in the crossed channel. -A resulto£ the enforcement of the Harari-Freund' conj.ecture for particle'-particle amplitudes is that the pomeron-pomeron-reggeon coupling is small. The model is tested phenomenologically by •(a) The analysis of --+ -1T p -1T p(1T 1T ) of Lipes, Robertson, and Zweig, (b) Baryon missing mass data at various energies. This. enables us to extract the• pomeron-particle total cross-section explicitly. •(c) The behavior of missing mass diffraction production peaks which are predicted to level off or dip near the :forward direction as a consequence of the vanishing of the triple pomeron coupling. -2-I. INTRODUCTION The discussion of the role of duality in inclusive reactions involves a generalization of the Harari-Freund (HF) conjecture 1 '
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.
Nuclear Physics B, 1973
The double-pomeron coupling strength ~'n tile dual resonance model is found in both the inclusive and exclusive regions by comparison with experiments. Double-pomeron coupling occurs in inclusive experiments in the Mueller diagram for the central plateau region. Its strength can also be bounded from its non-observation in the two-particle to four-particle exclusive experiments. The dual resonance model is used to perform the analytic continuation of a six-point amplitude between these regions. The results show that the coupling strength for two forward pomerons in the exclusive region must be less than 1 of that in the inclusive region. This is experimental evidence for substantial forward double-pomeron decoupling in exclusive processes.
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.
Measurements of single diffraction at √s = 630 GeV; Evidence for a non-linear α(t) of the pomeron
Nuclear Physics B, 1998
We report measurements of the inclusive differential cross section for the singlediffractive reactions: p i +p → p f + X and p +p i → X +p f at √ s = 630 GeV, in the momentum transfer range, 0.8 < −t < 2.0 GeV 2 and final state Feynmanx p > 0.90. Based on the assumption of factorization, several new features of the Pomeron Flux Factor are determined from simultaneous fits to our UA8 data and lower energy data from the CHLM collaboration at the CERN-Intersecting Storage Rings. Prominent among these is that the effective Pomeron Regge trajectory requires a term quadratic in t, with coefficient, α ′′ = 0.079±0.012 GeV −4. We also show that the data require a Pomeron-proton cross section that first decreases with increasing diffractive mass (corresponding to the PPR term in the triple-Regge expansion) and then increases at larger mass (the PPP term), similar to real particle total cross sections. We measure the product, Kσ 0 = 0.72 ± 0.10 mb GeV −2 , where K is the normalization constant of the Pomeron Flux Factor in the proton and σ 0 is the scale constant in the Pomeron-proton total cross section. Finally, we report the occurence of "beam jets" in the Pomeron direction in the rest frame of the diffractive system.
Phenomenological Analysis of the Pomeron-f Complex in Hadron Total Cross Sections
Progress of Theoretical Physics, 1977
Total cross sections in the range 6:s;;:pL:s;;:280 Ge V/ c are phenomenologically analyzed in order to extract symmetry properties of the Pomcron:f complex. The compatibility of a two component Pomeron with the second component contributing to NN, rrN and KN cross sections in the ratio 9 : 4 : 2 is shown. It is found that w:f exchange degeneracy critically depends on both f and Pomeron universality. Finally, it is demonstrated that one may interpret the Pomeron contribution as an enhanced cut and the f contribution as a halfenhanced cut as calculated by Gribov. § 1. Introduction A phenomenological analysis of hadron total cross sections in the momentum range of 6 to 280 Ge V / c had been previously performed 1 > in the frame\vork of Lipkin's') "two component" Pomeron ansatz, using a universal functional form for the Pomeron contribution. Lipkin's second component had been identified with the !-trajectory contributions in the framework of the algebra of vertex strengths."> The data were found to be compatible with universality, but not totally compatible with exchange degeneracy. An extension 1 >~ol of the analysis to forward and nonforward differential charge-exchange cross sections by several authors established compatibility of the parameter values derived from total cross sections, and independently confirmed the absence of strong p-A2 exchange degeneracy. Preliminary studies of forward elastic cross sectionsn confirm that a high value of a 1 (0) 1s compatible with the data. A more critical investigation of the oJ-j exchange degeneracy situation is necessary for several reasons. The p-A2 exchange degeneracy situation can easily be subjected to independent tests, since charge exchange cross sections dominated by p and A 2 exist. On the other hand, the !-trajectory has the quantum numbers of the vacuum, and its decoupling will inevitably involve additional assumptions and models concerning the nature of the Pomeron. The important question is beyond the simple assumption of exchange degeneracy. An understanding of the dynamics underlying the increase of total cross sections at high energy and the symmetry properties of this increase, at least on a phenomenological level is involved here. It is the purpose of the present investigation to attempt a clarification *l Research partially supported by the Scientific and Technical Research Council of Turkey.
We present a unied direct evaluation of the triple-pomeron coupling A 3IP (Q 2 ) for diractive real photoproduction (Q 2 = 0) and deep inelastic scattering at large Q 2 in the framework of the dipole approach to the generalized BFKL pomeron. We demonstrate how the reaction mechanism changes from diraction excitation of the constituent quarks of the photon at Q 2 = 0 to excitation of the octet-octet colour dipole state of the virtual photon at large Q 2 . The small phenomenological value of A 3IP (0), which w a s a m ystery, is related to the small non perturbative correlation radius R c 0:3 fm for the perturbative gluons. We conrm the early expectations of weak Q 2 dependence of the dimensionful coupling A 3IP (Q 2 ) and predict that it rises by a factor 1:6 from real photoproduction to deep inelastic scattering. *
Photon contribution to the “super-hard” pomeron
Physics Letters B, 1996
It is shown that direct photons provide a leading twist mechanism for diffractive jet production in which the jets carry away all of the momentum lost by the proton. Two-photon processes are thus expected to asymptotically dominate "super-hard" pomeron events in ep collisions. We report the expected rates from these events for the recent ZEUS and H1 data cuts. We also estimate the direct photon contribution to the "super-hard" pomeron events observed by the CERN UA8 group for pp collisions.
New anomalous exchange in Regge phenomenology and hard diffraction
Nuclear Physics B - Proceedings Supplements, 2001
A new mechanism for hard diffraction based on the anomalous f1 trajectory exchange, which we identify as the odd signature partner of the Pomeron, is suggested. We calculate the contribution of the f1 exchange to elastic and dissociative electromagnetic production of vector mesons and show that it gives a dominant contribution to the differential cross sections at large momentum transfers.
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.