Reggeon interactions in perturbative QCD

We study the pairwise interaction of reggeized gluons and quarks in the Regge limit of perturbative QCD. The interactions are represented as integral kernels in the transverse momentum space and as operators in the impact parameter space. We observe conformal symmetry and holomorphic factorization in all cases.     

Reggeon Field Theory phenomenology at collider energies

A complete phenomenological analysis of the applications of Critical Reggeon Field Theory at collider energies is presented. It includes total as well as different elastic cross sections, and the ratio real to imaginary part of the amplitude. Finite energy corrections have been taken into account to improve the agreement with the available SPS data. Predictions for the TEVATRON and future colliders at \(\sqrt s = 2\) , 10, 20, and 40 TeV are also presented. Some results concerning the perturbative version of Reggeon Field Theory are included. The general conclusion of the study is that SPS energies are still far from the truly asymptotic regime.     

f-Dominance of the Pomeron in Reggeon Field Theory

A Reggeon Field Theory (RFT) which incorporates the Pomeron and thef-pole is presented. The constrains on the renormalization group β-functions imposed by thef-dominance of the Pomeron are derived. We show that these constrains are satisfied by the RFT at least up to third order in the coupling constants.     

Hamiltonian for Reggeon interactions in QCD

It is shown, that the interaction of the reggeized gluons in the leading logarithmic approximation of the multicolour QCD has a number of remarkable properties including the duality symmetry. The duality relation for the Odderon wave function takes a form of the one-dimensional Schrödinger equation. It gives a possibility to express the Odderon Hamiltonian as a function of its integrals of motion.     

Eikonalization and unitarity constraints

An extensive generalization of the ordinary and quasi-eikonal methods is presented for the pp and elastic scattering amplitudes, which takes into account in a phenomenological way all intermediate multiparticle states involving the crossing even and crossing odd combinations of Reggeons. The formalism in this version involves a maximum of three parameters corresponding to the intermediate states which are possible in this configuration. The unitarity restriction is investigated and particular cases are discussed. An interesting result that emerges concerns the Odderon trajectory intercept: we find that unitarity dictates that this quantity must be below or equal unity unless a very peculiar equality exists between the coupling of the particles to the Pomeron and the Odderon. Received: 3 September 1999 / Revised version: 21 February 2000 / Published online: 8 May 2000 2000     

The Reggeon Field Theory and finite scales at collider energies

The Reggeon Field Theory (RFT) with attention paid to finite “flavoring” rapidity scales is considered in the light of emerging SPS collider data. Predictions from a simple RFT perturbative model made in 1978 are shown to be consistent with σ_tot and other data, in both theP?f identity andP+f versions. The RFT scaling laws are judged not applicable without large non-leading terms, implying an asymptotic region beyond the collider.     

Some Perturbative and Non-Perturbative Results Exposing Certain Field Aspects of Reggeon Field Theory

The present work is to discuss certain aspects of Reggeon field theory. Reggeon field theory demands special interest since the Reggeons are considered to be quasi particles of non-relativistic world. Scale symmetry has been applied in RFT effecting modification in the Re-normalization group equation (RGE) and the possible break down in the exact symmetry has been pointed out. The non-perturbative functional method has been applied to RFT under the Eikonal approximation resulting in an expected high energy behaviour.     

The Gribov Process: Soft Parton Interactions in So-Called Reggeon Field Theory

As shown in previous papers, Reggeon “Field” Theory is actually a Markov process describing the evolution of wee partons during a boost. In the present paper, the physical interpretation of scattering amplitudes and cross sections is discussed, both for the uncut (unlabelled) and cut (labelled) version. Elastic amplitudes and total cross sections, inclusive cross sections, fully diffractive events, and inelastic diffraction are all shown to have simple interpretations in the parton model. Finally, the connection with models for evolution of hard partons in QCD is discussed.     

An interplay between static potential and Reggeon trajectory for QCD string

I consider two cases where QCD string is described by an effective theory of long strings: the static potential and meson scattering amplitudes in the Regge regime. I show how they can be solved in the mean-field approximation, justified by the large number of space–time dimensions, and argue that it turns out to be exact. I compare contributions from QCD string and perturbative QCD and discuss experimental consequences for the scattering amplitudes.     

TheO(ɛ2) scaling law fordσ/dt in the Reggeon Field Theory

We calculate the two loop contributions within the ε-expansion to the Reggeon Field Theory scaling law fordσ/dt, derived using the renormalization group and a general renormalization point for the Pomeron propagator. This generalizes theO(ε) work of Abarbanel, Bartels, Bronzan, and Sidhu. The invariance of the results under certain coupling constant rescalings is demonstrated. We also make some qualitative comments regarding phenomenological applications. Our amplitude in a certain limit approximates the form of the low energy diffractive amplitude advocated by Kane.     

The content of unitarity constraints on a pomeron pole of intercept one

We present a consistent picture of a pomeron pole with intercept one, together with its cuts, which evades the decoupling arguments. We use the reggeon cut discontinuity formulae to introduce Gribov's reggeon calculus as an exact solution of multiparticle t-channel unitarity. We show how, within the calculus, two-pomeron iterations of a singular kernel can be responsible for the zero in the triple-pomeron vertex. Using the concept of a bare pomeron pole as a multiperipheral production process which is subsequently renormalised by other effects, we apply the reggeon calculus analysis to inclusive cross sections. We find that the inclusive sum rule decoupling arguments are avoided because of the addition of enhanced absorptive corrections to the conventional Regge pole contributions. However, we show that in this picture the combined pole and two-pomeron cut contribution to the total cross section factories to order (ln s)^?2.We also show that, when the correct helicity structure of the pomeron is taken into account, the s-channel unitarity condition for pomeron scattering amplitudes does not lead to any serious decouplings.     

Infrared behaviour and the bare Pomeron intercept in a Reggeon Field Theory including the Pomeron and thef-pole

An extension of the critical Reggeon Field Theory that includes both the Pomeron and thef-Reggeon fields is constructed. The quantum numbers of thef-Reggeon allows specific Reggeon-Pomeron couplings that have not been considered previously in standard works on secondary trajectories. We show the existence of a single fully stable fixed point among a total of 11 points. Unfortunately this point does not satisfy the factorization requirements imposed by thef-dominance of the Pomeron hypothesis and, in consequence, the critical Pomeron can not bef-dominated in aP+f model. We have also evaluated the value of the intercept of the bare critical Pomeron, using the method of integral representations of the propagators. The value obtained is clearly higher than the one previously obtained without thef-Pomeron interplay. With an adequate choice of the values of the bare coupling constants its value is in good agreement with the phenomenological one.     

Energy conservation constraints on multiplicity correlations in QCD jets

We compute analytically the effects of energy conservation on the self-similar structure of parton correlations in QCD jets. The calculations are performed both in the constant and running coupling cases. It is shown that the corrections are phenomenologically sizeable. On a theoretical ground, energy conservation constraints preserve the scaling properties of correlations in QCD jets beyond the leading log approximation.