Charm and bottom production in inclusive double Pomeron exchange in heavy ion collisions at the LHC

The inclusive double Pomeron exchange cross section for heavy quark pair production is calculated for nucleus-nucleus collisions at the LHC. The present estimate is based on hard diffractive factorization, corrected by absorptive corrections and nuclear effects. The theoretical uncertainties for nuclear collisions are investigated and a comparison to other approaches is presented. The production channels producing a similar final state configuration are discussed as well.Comment: 7 pages, 3 tables. Final version to be published in Physical Review

Charged rho meson production in neutrino-induced reactions at E_nu = 10 GeV

The neutrinoproduction of charged $\rho$ mesons on nuclei and nucleons is investigated for the first time at moderate energies ($\approx$ 10 GeV), using the date obtained with SKAT bubble chamber. No strong nuclear effects are observed in $\rho^+$ and $\rho^-$ production. The fractions of charged and neutral pions originating from $\rho$ decays are obtained and compared with higher energy data. From analysis of the obtained and available data on $\rho^+$ and $K^{*+}$(892) neutrinoproduction, the strangeness suppression factor in the quark string fragmentation is extracted: $\lambda_s = 0.18\pm0.03$. Estimations are obtained for cross sections of quasiexclusive single $\rho^+$ and coherent $\rho^+$ neutrinoproduction on nuclei. The estimated coherent cross section $\sigma_{\rho^+}^{coh}$ = (0.29$\pm0.16)\cdot 10^{-38}$ cm$^2$ is compatible with theoretical predictions.Comment: 7 pages, 6 figure

The yields of light meson resonances in neutrinonuclear interactions at <E_nu> = 10 GeV

The total yields of the all well-established light mesonic resonances (up to the $\phi$(1020) meson) are estimated in neutrinonuclear interactions at < E_nu > = 10 GeV, using the data obtained with SKAT bubble chamber. For some resonances, the yields in the forward and backward hemispheres in the hadronic c.m.s. are also extracted. From the comparison of the obtained and available higher-energy data, an indication is obtained that the resonance yields rise almost linearly as a function of the mean mass of the neutrinoproduced hadronic system. The fractions of pions originating from the light resonance decays are inferred.Comment: 15 pages, 7 figure

Bose-Einstein source of intermittency in hadronic interactions

The multi-particle Bose-Einstein correlations are the source of ''intermittency'' in high energy hadronic collisions. The power-law like increase of factorial moments with decreasing bin size was obtained by complete event weighing technique with gaussian approximation of space-time particle emitting source shape. The value of source size parameter was found to be higher than the common one fitted with the help of the standard Handbury Brown-Twiss procedure.Comment: 12

A study of the nuclear medium influence on transverse momentum of hadrons produced in deep inelastic neutrino scattering

The influence of nuclear effects on the transverse momentum $(p_T)$ distributions of neutrinoproduced hadrons is investigated using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam (with $E_{\nu}$ = 3-30 GeV) at Serpukhov accelerator. Dependences of $$on the kinematical variables of inclusive deep-inelastic scattering and of the produced hadrons are measured. It has been observed, that the nuclear effects cause an enhancement of$$ of hadrons (more pronounced for the positively charged ones) produced in the target fragmentation region at low invariant mass of the hadronic system (2 $< W <$ 4 GeV) or at low energies transferred to the current quark (2 $< \nu < 9$ GeV). At higher $W$ or $\nu$, no influence of nuclear effects on $$ is observed. Measurement results are compared with predictions of a simple model, incorporating secondary intranuclear interactions of hadrons (with a formation length extracted from the Lund fragmentation model), which qualitatively reproduces the main features of the data.Comment: 23 pages, 7 figure

Single - particle correlations in events with the total disintegration of nuclei

New experimental data on the behaviour of the single-particle two-dimensional correlation functions R versus Q (Q is the number of nucleons emitted from nuc- lei) and Ap (Ap is the mass of projectile nuclei) are presented in this paper. The interactions of protons, d, 4He and 12C nuclei with carbon nuclei (at a momentum of 4.2 A GeV/c) are considered.The values of R are obtained separately for pi minus mesons and protons.In so doing,the values of R are normalized so that -1=<R=<1.The value of R=0 corresponds to the case of the absence of corre- lations.It has been found that the Q- and Ap-dependence of R takes place only for weak correlations (R< 0.3).In the main (90 %),these correlations are con- nected with the variable pt and have a nonlinear character, that is the regi- ons with different characters of the Q-dependence of R are separated: there is a change of regimes in the Q-dependences of R.The correlations weaken with increasing Ap, and the variable R gets the least values of all the considered ones in 12CC interactions.Simultaneously with weakening the correlations in the region of large Q, the character of the Q-dependence of R changes.Comment: 17 pages, submitted to Phys. Rew.

The A - dependence of K0K^{0} and Λ\Lambda neutrinoproduction on nuclei

For the first time, the A- dependence of the production of $K^0$, $\Lambda$ and, for comparison, $\pi^-$ mesons is investigated in neutrinonuclear reactions, using the data obtained with SKAT bubble chamber. An exponential parametrization ($\sim A^{\beta}$) of the particle yields results in ${\beta}_{V^0} = 0.20 \pm 0.05$ for $V^0$ particles (combined $K^0$ and $\Lambda$), while for $\pi^-$ mesons the A- dependence is much weaker, ${\beta}_{\pi^-} = 0.068 \pm 0.007$. A nuclear enhancement of the ratio $K^0/\pi^-$ is found; this ratio increases from $0.055 \pm 0.013$ for $\nu N$- interactions up to $0.070 \pm 0.011$ at $A \approx 21$ and $0.099 \pm 0.011$ at $A \approx 45$. It is observed, that the multiplicity rise of $V^0$'s occures predominantely in the backward hemisphere of the hadronic c.m.s. It is shown, that the A- dependence of the nuclear enhancement of the ${\Lambda}^0$ and $\pi^-$ yields can be reproduced in the framework of a model, incorporating the secondary intranuclear interactions of pions originating from the primary $\nu N$- interactions, while only (29$\pm$9)% of that for $K^0$ at $A \approx 45$ can be attributed to intranuclear interactions.Comment: 18 pages, 8 figure

A Color Mutation Model of Soft Interaction in High Energy Hadronic Collisions

A comprehensive model, called ECOMB, is proposed to describe multiparticle production by soft interaction. It incorporates the eikonal formalism, parton model, color mutation, branching and recombination. The physics is conceptually opposite to the dynamics that underlies the fragmentation of a string. The partons are present initially in a hadronic collision; they form a single, large, color-neutral cluster until color mutation of the quarks leads to a fission of the cluster into two color-neutral subclusters. The mutation and branching processes continue until only $q\bar q$ pairs are left in each small cluster. The model contains self-similar dynamics and exhibits scaling behavior in the factorial moments. It can satisfactorily reproduce the intermittency data that no other model has been able to fit.Comment: 24 pages including 11 figures in revtex epsf styl

Behavior of the diffractive cross section in hadron-nucleus collisions

A phenomenological analysis of diffractive dissociation of nuclei in proton-nucleus and meson-nucleus collisions is presented. The theoretical approach employed here is able to take into account at once data of the HELIOS and EHS/NA22 collaborations that exhibit quite different atomic mass dependences. Possible extensions of this approach to hard diffraction in nuclear processes are also discussed.Comment: 5 pages, 2 figure

Systematics of Leading Particle Production

Using a QCD inspired model developed by our group for particle production, the Interacting Gluon Model (IGM), we have made a systematic analysis of all available data on leading particle spectra. These data include diffractive collisions and photoproduction at HERA. With a small number of parameters (essentially only the non-perturbative gluon-gluon cross section and the fraction of diffractive events) good agreement with data is found. We show that the difference between pion and proton leading spectra is due to their different gluon distributions. We predict a universality in the diffractive leading particle spectra in the large momentum region, which turns out to be independent of the incident energy and of the projectile type.Comment: 13 pages, Latex, 4 ps figures. To appear in Phys. Rev.