Partial inelasticities from the dual parton model

The question of the energy behavior of the partial inelasticities is studied in the context of the dual parton model. A simple analytical expression is derived which describes the behavior of the partial inelasticities at high energies. A comparison with the results of some other models is also given. The question of the violation of Feynman scaling is considered with reference to the inelasticity problem. Received: 8 August 1997 / Revised version: 12 December 1997 / Published online: 10 March 1998     

Smallp T particle production in the dual parton model

The rise in the ratio of the normalizedp _T distributions in smallp _T region at high multiplicities to that for minimum bias events, observed forpp collisions at \(\sqrt s = 63 GeV\) , is explained as a kinematical effect in the dual parton model. Our interpretation is rather general so that it can be applied to recent nucleus-nucleus experiments.     

Feynman scaling violation on baryon spectra in pp collisions at LHC and cosmic ray energies

A significant asymmetry in baryon/antibaryon yields in the central region of high energy collisions is observed when the initial state has nonzero baryon charge. This asymmetry is connected with the possibility of baryon charge diffusion in rapidity space. Such a diffusion should decrease the baryon charge in the fragmentation region and translate into the corresponding decrease of the multiplicity of leading baryons. As a result, a new mechanism for Feynman scaling violation in the fragmentation region is obtained. Another numerically more significant reason for the Feynman scaling violation comes from the fact that the average number of cut Pomerons increases with initial energy. We present the quantitative predictions of the Quark-Gluon String Model for the Feynman scaling violation at LHC energies and at even higher energies that can be important for cosmic ray physics.     

Strange particle production at RHIC in the dual parton model

We compute the mid-rapidity densities of pions, kaons, baryons and antibaryons in Au-Au collisions at GeV in the dual parton model supplemented with final state interaction (comovers interaction). The ratios ( ) increase between peripheral ( ) and central ( collisions by a factor 2.4 (2.0) for the , 4.8 (4.1) for the and 16.5 (13.5) for the . The ratio increases by a factor 1.3 in the same centrality range. A comparison with the available data is presented.Received: 28 April 2003, Published online: 11 July 2003     

Multiparticle correlations in a two component dual parton model

The dual parton model (DPM) describes soft and semihard multiparticle production. The presented version of the DPM includes soft and hard mechanisms as well as diffractive processes. The model is formulated as a Monte-Carlo event generator. We calculate, in the energy range of the hadron colliders, particle ratios as function of the transverse momentum, the rise of the average transverse momenta with the charged multiplicity, forward-backward correlations, short range correlations and factorial moments as function of the size of the pseudorapidity bins. For most of these quantities we find a reasonable agreement with experimental data.     

Single diffractive hadron-nucleus interactions within the dual parton model

Single diffractive hadron-nucleus interactions are studied within the framework of the dual parton model. Introducing a diffractive component into the Monte-Carlo event generator DTUNUC we investigate particle production and the dependence of the diffractive cross section on the atomic number of the target nucleus. A comparison of the numerical results with recent experimental data is presented. We furthermore introduce hadronic cross section fluctuations and discuss their influence on diffractive proton-nucleus cross sections.     

Analysis of the electroproduction structure functions in the lowQ 2 region,combining the vector meson dominance and the parton model with possible scaling violation

The nucleon structure functionF ₂ is constructed and analysed for low values ofQ ² using the generalised vector meson dominance representation with the largeQ ² spectral function calculated from the analytic continuation of the parton model structure function. Various parametrisations of the parton distributions are considered. Possible effects of the largeQ ² scaling violation on the lowQ ² part of the structure function are investigated. The magnitude of the total contribution given by this asymptotic part can be as high as 50% of the vector meson contribution in the low-Q ², low-χ region. The contribution of the valence quarks alone to the structure function at lowQ ² turns out to be at least as important as the corresponding non-Pomeron Regge-pole-like terms coming from the vector meson part. Increase of the structure function with ν coming from the increase of the quark sea in the limit of small χ implied by QCD turns out to be relatively weak at lowQ ². Predictions of the model are compared with available experimental data. The photoproduction cross section and the nuclear effects in the structure function are also briefly discussed.     

The multistring fragmentation model and violation of KNO scaling

The violation of Koba-Nielsen-Olesen scaling of the multiplicity distribution is studied in detail within the dual multistring fragmentation model. Comparison with recent data from the CERN-SPS proton-antiproton collider reveals a close agreement.     

Inclusive spectra of secondaries produced on nuclear targets at superhigh energies and with violation of Feynman scaling

Effects of Feynman scaling violation in yields of hadron secondaries inpA and πA collisions that arise when initial energy is increased are considered. There result from the growth of hadron-nucleon cross sections and an expected increase of the average transverse momenta of secondaries. The model of quark-gluon strings is used to calculate the inclusive spectra of secondaries. Interactions with a fixed number of nucleons are calculated, taking account of the growth of the slope parameter in elastichN scattering. Violation of Feynman scaling at superhigh energies turns out to be stronger than the additive quark model predicts it to be.     

Unified scaling law in the coherent noise model

The waiting time distribution between successive events and the unified scaling law is studied using the coherent noise model. It is shown that, although this model generates uncorrelated event sizes and does not exhibit criticality, it still provides the unified scaling law. We argue the role of characteristic kink observed in the unified scaling law and the meaning of the parameter C$C$ used to fix the peak of the kink to unity. Our results indicate that the parameter C$C$ is indeed a physical quantity localizing the end of the linear tendency in the scaling law, which corresponds to the completion of the dominance of correlated events in time.     

On methods of analyzing scaling violation in deep inelastic scattering

We discuss relative merits and shortcomings of various methods used in analyses of deep inelastic scattering data within the framework of leading twist QCD perturbation expansion. We advocate the use of Jacobi polynomials method as by far the simples, fastest and simultaneously very accurate way of analysing theQ ²-evolution of nucleon structure functions. Detailed comparison with the numerical solution of the corresponding evolution equation to the next-to-leading order is presented.     

Hadronic energy density in the dual parton model with formation zone intranuclear cascade

We study the evolution of the hadronic energy and particle density during central nucleus-nucleus collisions at various energies with a Monte Carlo version of the dual parton model. We find at RHIC and at LHC energies energy densities well in the range where the formation of quark gluon plasma is expected.     

Monte-Carlo dual parton model as analyzed by factorial moments and SBCFs

A Monte-Carlo implementation of the Dual Parton Model of multiparticle production is analyzed by means of scaled factorial moments and split-bin correlation functions. Correlations provided by multi-chain production and resonance decays are studied for different versions of the model. The model underestimates the Collider experimental data on factorial moments. Possible origins of the discrepancies are discussed.