Topological cross-section in hadron-nucleus collisions and multiple scattering theory

The multiple scattering theory supplemented with AGK cutting rules is applied to calculation of the hadron-nucleus interaction cross-sections. In contrast to standard Glauber approach neither smallness of the interaction radius compared to the nuclear radii nor Gaussian form of thehN-interaction profile function are assumed. We consistently use the theory of the supercritical Pomeron. However all the results are more general and do not depend on the specific parametrization of the Pomeron pole ampletude. The region of validity of the widely used approximate formulae for topological and totalhA-interaction cross sections are discussed. It is discussed the novel features of particle-nucleus interactions at superhigh energies.     

Coherent and incoherent particle production off nuclei at high energies

The Glauber-Gribov model for hadronnucleus scattering is extended to multiproduction processes by supplimenting it with the AGK cutting rules. In contrast to the standard Glauber approach neither smallness of the interaction radius compared to the nuclear radii nor Gaussian form of theh-N-interaction profile function are assumed. We consistently use the theory of superciritical Pomeron. However all the results are more general and do not depend on the specific parametrization of the Pomeron pole amplitude. The inelastic screening due to the low mass diffractive excitations is also included. The cross-sections of coherent and incoherent diffractive production of the low mass hadronic states are calculated. We comment on the novel features of particle-nucleus interactions at superhigh energies when the interaction region blows up to the nucleus size. Specifically, one encounters here the rapid rise of the coherent interaction cross-sections and strong suppression of incoherent quasielastic processes.     

A Pomeron model which needs no decoupling

We present a model in which the Pomeron is a related pair of factorizable Regge poles both with intercept one. Our model requires a cut (fixed or moving) with a branch point intercept one. In this model the triple Pomeron vertex need not vanish and as a result the Pomeron may couple to asymptotically constant cross sections. Our model can even fit pp elastic scattering data moderately well.     

Light-by-light scattering in double-logarithmic approximation

In the present paper we consider the elastic \(2 \rightarrow 2\) -scattering of virtual photons at high energies in the forward kinematics at zero and non-zero values of t. Accounting for both gluon and quark double-logarithmic (DL) contributions to all orders in the QCD coupling, we obtain explicit expressions for amplitudes of this process in double-logarithmic approximation (DLA). First we keep the QCD coupling fixed and then account for running coupling effects. Applying the saddle-point method to the obtained expressions for the scattering amplitude, we calculate the high-energy asymptotics of the amplitude, which proved to be of the Regge form. The Reggeon bears the vacuum quantum numbers and therefore it is a new, DL contribution to Pomeron. Comparison of the DL Pomeron to the BFKL Pomeron shows that contribution of the DL Pomeron to the high-energy asymptotics is of the same order as contribution of the BFKL Pomeron, so the DL Pomeron should be taken into account together with the BFKL Pomeron. We estimate the applicability region for the asymptotics of the light-by-light scattering amplitude, where the the DL Pomeron can reliably represent the parent amplitude.     

High Energy Proton-Proton Elastic Scattering in the Pomeron Exchange Model

We study high energy proton-proton elastic scattering in the framework of Pomeron exchange model. The cross section of the process are calculated without any free parameters. Our finding is that Pomeron exchange theory gives perfect fits to total cross section at the energy of√s higher than 10 GeV and to differential cross section at the momentum transfer [t] less than 1.5 GeV2. For total cross section at lower energy √s ＜ 10 GeV and differential cross section at larger momentum transfer region of |t| ＞ 1.5 GeV2, the Pomeron exchange theory needs to be improved.     

High Energy Proton-Proton Elastic Scattering in the Pomeron Exchange Model

We study high energy proton-proton elastic scattering in the framework of Pomeron exchange model. The cross section of the process are calculated without any free parameters. Our finding is that Pomeron exchange theory gives perfect fits to total cross section at the energy of √(s) higher than 10 GeV and to differential cross section at the momentum transfer |t| less than 1.5 GeV². For total cross section at lower energy √(s)<10 GeV and differential cross section at larger momentum transfer region of |t|>1.5 GeV², the Pomeron exchange theory needs to be improved.     

Reggeon, Pomeron and Glueball, Odderon-Hadron-Hadron Interaction at High Energies - From Regge Theory to Quantum Chromodynamics

Based on analysis of scattering matrix S, and its properties such as analyticity, unitarity, Lorentz invariance, and crossing symmetry relation, the Regge theory was proposed to describe hadron-hadron scattering at high energies before the advent of QCD, and correspondingly a Reggeon concept was born as a mediator of strongly interaction. This theory serves as a successful approach and has explained a great number of experimental data successfully, which proves that the Regge theory can be regarded as a basic theory of hadron interaction at high energies and its validity in many applications. However, as new experimental data come out, we have some difficulties in explaining the data. The new experimental total cross section violates the predictions of Regge theory, which shows that Regge formalism is limited in its applications to high energy data. To understand new experimental measurements, a new exchange theory was consequently born and its mediator is called Pomeron, which has vacuum quantum numbers. The new theory named as Pomeron exchange theory which reproduces the new experimental data of diffractive processes successfully. There are two exchange mediators： Reggeon and Pomeron. Reggeon exchange theory can only produce data at the relatively lower energy region, while Pomeron exchange theory fits the data only at higher-energy region, separately. In order to explain the data in the whole energy region, we propose a Reggeon-Pomeron model to describe high-energy hadron- hadron scattering and other diffractive processes. Although the Reggeon-Pomeron model is successful in describing high-energy hadron-hadron interaction in the whole energy region, it is a phenomenological model. After the advent of QCD, people try to reveal the mystery of the phenomenological theory from QCD since hadron-hadron processes is a strong interaction, which is believed to be described by QCD. According to this point of view, we study the QCD nature of Reggeon and Pomeron. We claim that the Reggeon exchange is an exchange of mult     

Higher order terms in the ϵ expansion of the pomeron propagator

The indices η, ν and γ which characterize the high energy behavior of the elastic scattering amplitude in the presence of a nonvanishing triple Pomeron interaction are calculated to order ?² where 4 - ? is the dimension of the space of transverse momenta.     

Dual Pomeron Amplitude with External Spin Particles

On the basis of the operator-formulation of the conventional dual resonance model we derive an expression for the one-loop Pomeron exchange amplitude with four external excited particles lying on the parent Regge trajectory. Evaluation of the high energy behaviour leads to the definition of spin-spin-Pomeron form factors. There is a leading Pomeron contribution only if the sum of external spins is even. The dual Pomeron does not exhibit any helicity conservation properties except for s-channel forward scattering. The extension to multiloop amplitudes is briefly discussed.     

关于软玻密子的结构

本文修改了Landshoff-Nachtmann的软玻密子(Pomeron P)场论模型.从强子组分夸克具有结构的观点出发,根据高能强作用软过程中的最大非微扰强作用反应假定,提出了有关软P新的结构图像.对撞强子中的一对组分夸克被分解为裸夸克和一系列非微扰胶子(和夸克对).与此相应,软P的结构是由胶子形成的一系列切割梯形图之和所代表.在系统能量s很大而动量转移|t|很小的多重雷吉(Regge)运动学区间,并在保留lns的领头阶近似下,计算了这组切割梯形图之和所对应的散射振幅和总截面.它们的表达式出现了对s的Regge型幂次因子,得出了软P轨迹的简洁表达式.简单说明了按本文提出的方案可以讨论那些相关的强作用过程.     

Diffusion and the BFKL pomeron

We study the high energy behaviour of elastic scattering amplitudes within the leading logarithm approximation. In particular, we cast the amplitude in a form which allows us to study the internal dynamics of the BFKL Pomeron for general momentum transfer. We demonstrate that the momentum transfer acts as an effective infrared cut-off which ensures that the dominant contribution arises from short distance physics.     

Regge field theory in zero transverse dimensions: loops versus “net” diagrams

Toy models of interacting Pomerons with triple and quaternary Pomeron vertices in zero transverse dimension are investigated. Numerical solutions for eigenvalues and eigenfunctions of the corresponding Hamiltonians are obtained, providing the quantum solution for the scattering amplitude in both models. The equations of motion of the theories are also considered and the classical solutions of the equations are found. Full two-point Green functions (“effective” Pomeron propagator) and amplitude of diffractive dissociation process are calculated in the framework of RFT-0 approach. The importance of the loops contribution in the amplitude at different values of the model parameters is discussed as well as the difference between the models with and without quaternary Pomeron vertex.     

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.     

Reggeon field theory: Formulation and use

We formulate and discuss Reggeon field theory, which enables one to systematically analyze the exchange of Regge poles and associated branch points in high energy hardron scattering. The field theory is first motivated by a consideration of hybrid Feynman graphs, and then a more general derivation from crossed-channel multiparticle unitarity relations is given. Rules for Reggeon interaction and propagation are formulated. We treat in some detail the problem of the Pomeron or vacuum pole which has α(0) = 1 and is responsible for diffractive processes. In particular the renormalization group analysis of Reggeon field theory is presented and the structure of Pomeron partial wave amplitudes is elucidated. Also the question of Pomeron or absorptive corrections to secondary trajectories (both fermion and boson) is considered. We make some comments on important problems yet remaining in Reggeon field theory; in particular, we stress the study of its s-channel content.     

THE DUAL ABSORPTIVE MODE AND πP ELASTIC SCATTERING REVISITED

Using the Regge pole phase rule for contrilbutions to both amplitudes the DAM is applied to ^πp elastic scattering in the p_lab≥10 GeV/c and |t|≤0.8(GeV/c)² region. It is found that the DAM has a mixed success in describing ^πp scattering. The p contribution to both amplitudes is in accord with the DAM while the f-non-flip contribution does not have a peripheral zero.The Pomeron imaginary part is in accord with the DAM with a non-negligible Pomeron phase so that the DAM approximation Rep=O is unsatisfactory. There is also a Pomeron-flip contribution contrary to the expectation of the model. The O-flip contribution is taken into account and a small f-flip contribution i s also required.     

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 scattering in a two-dimensional gauge theory

We study high-energy scattering in two-dimensional quantum chromodynamics in the 1/N_colour expansion. To first order, high-energy forward scattering amplitudes are power-behaved with the factorization, signature and exchange degeneracy properties found in dual Regge models. Backward scattering has deviations from naive quark power-counting rules which are related to the form factor and “Regge” behaviours. In the second order of 1/N_colour vacuum exchange diagrams do not give a new Pomeron singularity, but do break exchange degeneracy.     

Phenomenology of Elastic Hadron Diffraction

Recent experimental data on high-energy elastic scattering of hadrons is reviewed in the light of various theoretical models with special emphasize on the dipole (or geometrical) Pomeron. As suggested by its name, this model combines the properties of two different approaches: the analytic and geometric ones. Its virtue is simplicity, which makes possible analytic calculation of many complicated problems.     

Pomeron的胶子内容

指出Pomeron可以被看作为具有Regge轨道α_p(t)=1.08+0.2GeV^－2t的Regge化的胶子球.理论成功地预言了实验上观测到的质子一质子弹性散射的总截面.理论与实验的最好符合给出了张量胶子球到质子反质子道的衰变宽度为9±3MeV,其总宽度大于50MeV.并且排除了张量胶子球的自旋为4的可能性.     

Pomeron-Quark Coupling from Charge Conjugation Invariance

Based on the charge conjugation invariance and the vazuum property of the Pomeron, we point out that the commonly used vector vertex of the Pomeron coupling to quarkis incorrect since it contradicts with the Pomeron property. We also claim that the soft Pomeron could be a tensor glueball ξ（2230） with quantum numbers I^GJ^PC = 0^＋2^＋＋ and total decay width Гtot ≌ 100 MeV, which lies on the soft Pomeron trajectory αp = 1.08＋ 0.20t. Therefore, the coupling vertex of the soft Pomeron to quark should be tensorial which is invariant under the charge conjugation and can explaIn why the inadequate vector coupling, γ^μ, of the soft Pomeron to quark is successful in dealing with Pomeron physics.