Reggeon Theory Research Articles

Local one-dimensional reggeon model of the interaction of several pomerons

We consider the one-dimensional local reggeon theory describing the leading pomeron with the conformal spin l=0 and two subdominant pomerons with l=pm 2. The dependence of the propagators of pomerons and the hA amplitude on rapidity are found numerically by integrating the evolution equation.

Local one-dimensional reggeon model of the interaction of pomerons and odderons

We propose the one-dimensional reggeon theory describing local pomerons and odderons. It generalizes the well-known one-dimensional theory of pomerons (the Gribov model) and includes only triple interaction vertices. The proposed theory is studied by numerical methods: the one-particle pomeron and odderon propagators and the pA amplitude are found as functions of rapidity by integrating the evolution equation.

Elliptical flows in Reggeon theory

A new mechanism for the generation of an azimuthal anisotropy of particles produced in heavy-ion collisions is analyzed. An analysis is performed within Reggeon theory and is general. The resulting effect can be interpreted in terms of the partonic structure of a fast nucleus. This mechanismcan contribute significantly to the observed value of the elliptic flow υ2. The dynamics in question differs significantly from a standard mechanism of the collective motion of a hadron medium after a collision.

Strong interactions at high energies in the Reggeon approach

A brief survey of the development of Reggeon theory at ITEP and its application to hadron interactions at high energies is given. Basic properties of Regge poles and moving branch points and their relation to multiparticle hadron production are discussed. The one-pion-exchange model for describing exclusive and inclusive processes is considered. Basic properties of the model of quark-gluon strings and its applications are described. Reggeon field theory, its various asymptotic regimes, and its relation to diffractive phenomena are examined. The important role of Pomeron interactions in the theory of the supercritical Pomeron and their manifestations in the theory of deep-inelastic electron scattering and in heavy-ion collisions are discussed.

The partonic interpretation of reggeon theory models

We review the physical content of the two simplest models of reggeon field theory: namely the eikonal and the Schwimmer models. The AGK cutting rules are used to obtain the inclusive, the inelastic and the diffractive cross sections. The system of non-linear equations for these cross sections is written down and analytic expressions for its solution are obtained. We derive the rapidity gap dependence of the differential cross sections for diffractive dissociation in the Schwimmer model and in its eikonalized extension. The results are interpreted from the partonic viewpoint of the interaction at high energies.

The problem of “saturation” in DIS and heavy-ion collisions

The problem of saturation of parton densities in deep inelastic scattering (DIS) in the limit x → 0 and in heavy-ion collisions at very high energies is investigated in the framework of Reggeon theory. It is emphasized that the shadowing effects are important in a definite kinematical region. The model which includes unitarity effects and gives a good description of structure functions and diffractive processes in DIS is discussed. In the limit x → 0, the “saturation” of parton densities is achieved. The Gribov approach to interaction with nuclei allows one to describe structure functions of nuclei in the small-x region. It is shown how the prediction of the Glauber model for the density of hadrons produced in the central rapidity region in nucleus-nucleus interactions is modified due to shadowing of small-x partons. Calculations show that shadowing effects are important at RHIC energies, but the situation is far from saturation. Production of particles with large transverse momenta and jets is discussed.

On the Bose-Einstein correlation in inelastic collisions of nuclei

The Bose-Einstein correlation function for two pions of same charge produced in a high energy nucleus-nucleus collision is computed in the framework of the reggeon theory. We obtain a coherence parameter λ=1 and a transverse radius of the sourceR T close to the radius of the smaller of the colliding nuclei.

Unitarity corrections to short-range order: Long-range rapidity correlations

Although the effective hadronic forces have short range in rapidity space, one nevertheless expects long-range dynamical correlations induced by unitarity constraints. This paper contains a thorough discussion of long-range rapidity correlations in high-multiplicity events. In particular, we analyze in detail the forward-backward multiplicity correlations, measured recently in the whole CERN ISR energy range. We find from these data that thee normalized variance of the number n of exchanged cut Pomerons, , is most probably in the range 0.32 to 0.36. We show that such a number is obtained from Reggeon theory in the eikonal approximation. We also predict a very specific violation of local compensation of charge in multiparticle events: The violation should appear in the fourth-order zone correlation function and is absent in the second-order correlation function, the only one measured until now.

Inclusive distributions for Reggeon theory on a transverse lattice

We compute high-energy inclusive distributions for a pomeron intercept α larger than one. The framework is cut reggeon field theory (CRFT) where the inclusive amplitudes are expressed in terms of certain mass insertion Green functions. We generalize to CRFT the spin model on a transverse lattice recently proposed for Gribov's theory. We show that, for α > 1 there are four states degenerate with the “perturbative vacuum” φ 0. Local operators, such as creation of pomerons and mass insertions, acting on the φ 0 vacuum, generate a disturbance that expands in transverse space toward one of the other vacua with definite velocity. The study of this dynamical vacuum instability, similar to the one of Gribov's theory, allows to evaluate the inclusive distributions, which in one transverse dimension and for α very large, are computed exactly. The resulting distributions violate logarithmically Feynman scaling and have long range correlations. Inelastic unitary is satisfied in the form of energy-momentum conservation and positivity of cross sections. We discuss also the generalization to higher transverse dimensions and smaller α.

Partons, the gambler's ruin, and pomerons

The parton picture of Regge theory is extended to the supercritical case α p > 1. The essential results of Amati et al. and others are rederived by heuristic but mathematically very simple arguments. In addition, also some new results are obtained, in particular concerning the rôle of Pumplin's bound in reggeon theory. The transition between sub- and supercritical pomerons appears as a transition from total to partial ruin in a collective risk problem. In the subcritical case, some problems are encountered whose origin is not yet clear.

On the self-consistent Pomeron pole

A model is considered in which a Pomeron is regarded as a self-consistent intercept one Regge pole resulting from a Bethe-Salpeter-like equation in Reggeon theory. The absorptive nature of a two Pomeron cut is crucial for realization of self-consistency. For zero mass Pomerons the model predicts the vanishing of the triple Pomeron coupling and softening of Pomeron cut contributions to inclusive reactions in triple and di-triple Regge regions.

High energy pp data and the reggeon theory of diffraction scattering

Recent proton-proton scattering experiments from the CERN ISR show several striking features. There is strong evidence that the total cross section is rising. The elastic differential cross section shows a break in the forward slope, as well as a pronounced dip-bump structure, with the dip located at t ≅ − 1.3 (GeV/ c) 2. We demonstrate that all these features and their energy dependence can be simultaneously and quantitatively very well described within the framework of Gribov reggeon calculus.