Duality and symmetry tests for multiparticle production models

Two-body absorptive parts generated by unitarity from multi-Regge particle production models are tested with respect to duality and symmetry structure (suppression of exotics and exchange degeneracy in output). A multi-Regge model with production of only stable particles generates exotic and non-exotic outputs of equal strength; resonances (clusters) are needed to pass these symmetry tests. Two complementary approaches are used, explicit S-matrix models and duality diagrams; the connection between dynamical assumptions and different duality diagram rules is discussed. C-parity plays a crucial role; using C-conserving duality diagrams we show that standard manipulations lead to a topological pomeron which has secondary terms; one, with C_t = ?1, cancels the topological ω₁ meson, another one, with C_t = +1, cancels the topological ?₁ meson.     

New tests of multiparticle production models

The two quantities known in statistical theory as the median and modal multiplicities form a better basis than the multiplicity moments for tests of multiparticle production models, and distinguish clearly between multiperipheral and diffractive models. The data indicate multiperipheral dominance.     

Cluster models against new and old experimental data on multiparticle production

We analyze in the cluster model framework not only recent data on zones, rapidity gap distributions and charge transfer correlations in multiparticle production, but also data on “older” quantities, in particular on inclusive and semi-inclusive longitudinal correlations. We show that a global analysis of experimental results strongly constrains the cluster characteristics. High intracluster multiplicities are definitely excluded while about 50 to 60% of clusters have to carry an electric charge; these conclusions show that well-known mesonic resonance production may indeed account for a large part of clustering.     

Energy dependence of multiplicity in proton-nucleus collisions and models of multiparticle production

This is a continuation of our earlier investigation (Gurtuet al 1974Phys. Lett. 50 B 391) on multiparticle production in proton-nucleus collisions based on an exposure of emulsion stack to 200 GeV/c beam at the NAL. It is found that the ratioR _em = 〈n _s〉/〈n _ch〉, where 〈n _ch〉 is the charged particle multiplicity in pp-collisions, increases slowly from about 1 at 10 GeV/c to 1·6 at 68 GeV/c and attains a constant value of 1·71 ± 0·04 in the region 200 to 8000 GeV/c. Furthermore,R _em = 1·71 implies an effectiveA-dependence ofR _A =A ^0.18,i.e., a very weak dependence. Predictions ofR _em on various models are discussed and compared with the emulsion data. Data seem to favour models of hadron-nucleon collisions in which production of particles takes place through adouble step mechanism,e.g., diffractive excitation, hydrodynamical and energy flux cascade as opposed to models which envisage instantaneous production.     

Semiclassical approach for multiparticle production in scalar theories

We propose a semiclassical approach to calculate multiparticle cross sections in scalar theories, which have been strongly argued to have the exponential form exp(λ⁻¹ F(λn, ϵ)) in the regime λ → 0, λn, ϵ = fixed, where λ is the scalar coupling, n is the number of produced particles, and ϵ is the kinetic energy per final particle. The formalism is based on singular solutions to the field equation, which satisfy certain boundary and extremizing conditions. At low multiplicities and small kinetic energies per final particle we reproduce in the framework of this formalism the main perturbative results. We also obtain a lower bound on the tree-level cross section in the ultra-relativistic regime.     

Associated multiparticle production and intra-nuclear cascading

In the existing experiments on multiparticle production off nuclei it is difficult to distinguish between intra-nuclear cascading of secondaries and the other mechanisms of production which give important information on the short-time development of hadronic interactions. It is argued that by selecting nuclear interactions with no or little shadowing one can unambiguously establish the existence (or lack) of intra-nuclear cascading. It is suggested that investigation of associated particle production in the photoproduction of heavy vector mesons from nuclei and in inelastic lepton-nucleus interactions is a promising method of analyzing intranuclear cascading.     

Random cascading models and the link between long-range and short-range interactions in multiparticle production

A general recursive relation for the total multiplicity distribution is derived from a random cascading model with intermittency. The conditions for the existence of a fixed point solution are formulated. An explicit example of such a solution, corresponding to the negative binomial multiplicity distribution is presented. The intimate connection between random cascading models and models of disordered systems is explained and explored. Long-distance properties of the interaction are related to the spectrum of states describing the interaction at short range.     

Evolution of clans in multiparticle production

An alternative interpretation of the development of the clan structure arising formally from the natural decomposition of the negative binomial multiplicity distribution is presented here. Our approach is based on stochastico-physical ideas of multiple production on the parton level. Specific differential-difference evolution equations have been proposed which besides the elementary processes involving the ingredients of QCD branching describe collective phenomena of clan's collapsing and clan's coherent disintegration.     

Azimuthal correlations in high-energy multiparticle production

Some features of the two-particle correlation phenomena, studied by means of azimuthal angle variables, are discussed. Assuming Gaussian forms for the single transverse momentum distributions, it is proposed to described the two-particle correlation with only one parameter. The influence of the kinematical constraints on the proposed correlation parameter is discussed, using a limited transverse momentum phase-space model.     

Finite-size scaling in the multiparticle production

The finite-size scalling analysis of the scaled factorial moment data is proposed. This analysis allows to extract the scaling indices of the underlying higher-dimensional scale-invariant multiparticle distributions. Moreover, it exhibits the change of the effective scale involved in the dimensional projection with transverse momentum cuts applied to the data.     

Multifractality and high energy multiparticle production

The multifractal behaviours of the various types of high energy collisions are analyzed using the normalized factorial moments which are calculated from the experimental data. Thef() curves for the various types of collision are constructed. The width of thef() curves seems to indicate roughly degree of intermittency or fluctuation of the data. The width of the curves also does not seem to be affected by the energy.     

Charge and strangeness transfer in multiparticle production

A simple explicit model for charge production is found to agree well with available data. This model combined with unitarity gives a realistic estimate for the suppression of two-body charge exchange scattering. Similar considerations are applied to strangeness transfer.     

Intermittency in multiparticle production at high energy

We present predictions of random cascading models for multiparticle production at high energy. Standard and correlated factorial moments in rapidity are shown to provide stringent tests of the intermittency patterns characteristic of random cascades. Using the central limit theorem we show how to test directly for the existence of a cascading process. Finally, we discuss how to take into account statistical corrections.