Topological cross sections in hadron-nucleon and hadron-nucleus collisions at very high energies

We apply our microscopic model for the topological cross section σ_n to produce n charged particles in hadron-proton interactions to hadron-nucleus scattering. The model is based on a stochastic branching process for hadronization. We calculate multiplicity distributions of hadron-nucleus collisions for 50 GeV ? E_L ? 400 GeV based on a multiple collision model. The production of “grey” $\text{(0.3 <}\text{ν}\text{c}\text{< 0.7)}$ particles is considered together with the shower $\text{(}\text{ν}\text{c}\text{> 0.7)}$ particles in order to test the model for higher number of collisions. The joint probability distribution of numbers of shower and grey particles F(n_s, n_g) is calculated. Finally, we critically compare the results to experimental data.     

Colour confinement in hadron-nucleus collisions

We study the evolution of colour confinement in hadron-nucleus collisions and determine the resultingx _F dependence for the suppression of quarkonium production on nuclear targets. The Landau-Pomeranchuk effect applied to colour bremsstrahlung is shown to play a considerable role in the from of the suppression.     

Rescattering effects in hadron-nucleus and heavy-ion collisions

We review the extension of the factorization formalism of perturbative QCD to coherent soft rescattering associated with hard scattering in high energy nuclear collisions. We emphasize the ability to quantify high order corrections and the predictive power of the factorization approach in terms of universal non-perturbative matrix elements. Although coherent rescattering effects are power suppressed by the hard scales of the scattering, they are enhanced by the nuclear size and could play an important role in understanding the novel nuclear dependence observed in high energy nuclear collisions.Arrival of the final proofs: 22 July 2005PACS: 12.38.Bx, 12.39.St, 24.85. + p     

Application of nonperturbative quantum field theoretic methods to hadron-nucleus collisions: Background theory

An exposition of the background theory necessary for understanding the application of nonperturbative QFT methods (LSZ reduction formalism) to hadron-nucleus collisions, for example the derivation of pi-nucleus (πn) Low and Chew Low equations, is given. The many channels and complex targets on the one hand, and the quantized field interactions on the other, introduce subtleties not well covered in particle theory or potential scattering literature. By specializing the πn Low Equation we derive a “pi-nucleon Low equation in the nuclear medium.” The second main goal of the paper is to compare this equation with Dover and Lemmer's analogous equation arrived at by graphical arguments. This requires especially making explicit the analyticity properties left tacit in their work. In is concluded that the two are essentially different.     

Nuclear effects in lepton-pair production in hadron-nucleus collisions

The results of experimental investigations of Drell-Yan dimuon production in pBe and pW collisions at an energy of 800 GeV on a fixed target are analyzed. The ratios of the inclusive differential cross sections for lepton-pair production are calculated. It is shown that allowance for the effect of multiple soft rescattering of a projectile-hadron quark inside the target nucleus improves agreement between theoretical and experimental results.     

AGK cutting rules and multiple scattering in hadronic collisions

We discuss the AGK rules for the exchange of an arbitrary number of reggeized gluons in perturbative QCD in the high-energy limit. The results include the cancellation of corrections to single jet and double jet inclusive cross sections, both for hard and soft rescattering contributions.Received: 22 March 2005, Published online: 31 May 2005     

Target fragmentation in hadron-nucleus collisions at high energy

We discuss target fragmentations in hadron-nucleus collisions at high energy (5–400 GeV). A model is developed which is based on the two-step (fast and slow) processes. A high-energy hadron drills a linear hole inside the nucleus, kicking out several nucleons (fast process). Along the linear hole, the target breaks up into a few pieces. One of the fragments forms an observed nucleus, absorbing some of the recoil nucleons (slow process). During the breakup, the Coulomb interaction between the fragment and the rest is taken into account. This leads to the consideration of a three-body breakup process which influences significantly the low-energy part of the energy distribution in the h+A → B+X reaction. The model is applied to the angular and the energy distributions in this collision. It achieves a nice agreement with experiment.     

Dispersion of the multiplicity distribution in hadron-nucleus collisions

It is argued that the measurements of the dispersion of the multiplicity distribution in hadron-nucleus collisions favour the processes of particle production in a sequence of collisions of the incident hadron with target nucleons. On the other hand, generation of particles on groups of nucleons treated as single units leads to large discrepancies.     

Projectile fragmentation in hadron-nucleus collisions at high energies

Particle production in hadron-nucleus collisions at high energies is discussed in the projectile fragmentation region. The predictions of the constituent quark model are analyzed. The contribution of diffractive interactions is explicitly taken into account. Comparison with the recent Fermilab measurements shows good agreement with the quark model and strong effects of diffractive collisions in some of the analyzed reactions.     

Multiparticle production in hadron-nucleus collisions around 100 GeV

Experimental results of various groups are analysed in order to establish empirical laws on how the multiplicity and rapidity distributions of produced particles depend on the nature of the projectile hadron, its energy E and on the number v of struck nucleons. Global observables of these distributions (mean multiplicity, mean rapidity and variances) are parametrized. The parameters which govern the effects of multiple scattering are found independent of the energy E and of the nature of the hadron. Then, using identical hadron-nucleon input data, we evaluate the predictions of eight theoretical models and compare them with the empirical laws. Some models can be ruled out, while others, though based on very different physical assumptions, are compatible with experiment.     

Cluster model of cumulative particle production in hadron-nucleus collisions

The cumulative π-meson origin in nucleon-nucleus collisions is explained on the basis of a cluster model, and their energy spectra are described.     

Multiplicity correlations of medium energy protons in hadron-nucleus collisions

Data on forward-backward multiplicity correlations of medium energy protons from hadron-nucleus collisions are presented and discussed.     

Inclusive two-and three-particle rapidity correlations in high-energy hadron-nucleus collisions

Three-particle pseudorapidity correlations are investigated for relativistic secondaries from proton-nucleus interactions at 50, 67, 200 and 400 GeV/c and from pion-nucleus interactions at 50 and 200 GeV/c. The experimental data on two- and three-particle correlations are compared with quantitative predictions of current multiple scattering models of nuclear production. Within these models the influence of various factors on the magnitude of correlations is discussed and it is shown, in particular, that energy-momentum conservation plays an essential role at present accelerator energies.     

Inclusive hadron-nucleus scattering at high energy

The multiple scattering series of Glauber and Matthiae for hadron-nucleus scattering is summed to a simple analytical expression. It reproduces quantitatively the main features of the experimental cross section for the reaction ${}^4\text{He}\text{+}{}^{\mathrm{A}}\text{Z →}{}^4\text{He + X}$ at 1 GeV/nucleon.     

Particle production in hadron-nucleus collisions in a multi-chain fragmentation model

Zeitschrift für Physik C Particles and Fields - We investigate a multi-chain fragmentation model for particle production in hadron-hardon and hadron-nucleus collisions for all kinds of...     

Angular and energy distributions of grey particles in high-energy hadron-nucleus collisions

The angular and energy distributions of grey particles (mostly protons in the energy range 30–400 MeV) emitted in the interactions of high energy hadrons with nuclei are investigated here. Grey particles “g particles” are assumed to result from the intranuclear cascade initiated by the passage of the incident hadron through the target nucleus. Using the pretested hypothesis that these particles arise only from the first two generations of the cascade, we calculate their angular and energy distributions. Various experimental data are successfully described both in shape and absolute magnitude.