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Starting with the Strongly Correlated Quark Model (SCQM) of a hadron structure, SCQM, we propose a possible scenario of modification of the properties of mesons and baryons in a dense nuclear environment. These in-medium modifications can lead to the observable effects in heavy ion collisions, such as enhancement of strangeness and dropping/broadening vector meson masses.

To provide the computer simulation support to the new experimental facilities BM@N and MPD at the accelerator complex NICA we performed an upgrade of the Monte Carlo generator DCM-QGSM and developed a new generator, DCM-SMM, on the basis of the Dubna cascade model (DCM). The generators aimed to simulate particle–nucleus and nucleus–nucleus collisions in a wide range of energy and thus can serve as an effective tool for analysis of physical effects. A particularity of the generators is their capability to simulate nuclear fragments.

Particle knockout scattering experiments1,2 are fundamental for mapping the structure of atomic nuclei2–6, but their interpretation is often complicated by initial- and final-state interactions of the incoming and scattered particles1,2,7–9. Such interactions lead to reduction in the scattered particle flux and distort their kinematics. Here we overcome this limitation by measuring the quasi-free scattering of 48 GeV c–1 12C ions from hydrogen. The distribution of single protons is studied by detecting two protons at large angles in coincidence with an intact 11B nucleus. The 11B detection suppresses the otherwise large distortions of reconstructed single-proton distributions induced by initial- and final-state interactions. By further detecting residual 10B and 10Be nuclei, we also identified short-range correlated nucleon–nucleon pairs9–13 and provide direct experimental evidence for separation of the pair wavefunction from that of the residual many-body nuclear system9,14. All measured reactions are well described by theoretical calculations that include no distortions from the initial- and final-state interactions. Our results showcase the ability to study the short-distance structure of short-lived radioactive nuclei at the forthcoming Facility for Antiproton and Ion Research (FAIR)15 and Facility for Rare Isotope Beams (FRIB)16 facilities, which is relevant for understanding the structure and properties of nuclei far from stability and the formation of visible matter in the Universe. Initial- and final-state interactions distort the kinematics in particle knockout scattering experiments, complicating their interpretation. These effects are suppressed by detecting 11B nuclei in quasi-free scattering of 12C ions from hydrogen.

The new monte-carlo generator of heavy ion collisions, DCM-SMM, based on Dubna Cascade Model (DCM-QGSM) and Statistical Multifragmentation Model (SMM) is described. The model aimed to generate particle--nucleus and nucleus--nucleus collisions at a wide range of energy was created to provide the computer simulation support to new experimental facilities BMN and MPD at the accelerator complex NICA. It can simulate the production of both light particles and nuclear fragments and hyperfragments on the event by event basis., Comment: 33 pages, 16 figures. arXiv admin note: text overlap with arXiv:0806.3455

The article presents the concept of JINR Corporate Information System (JINR CIS). Special attention is given to the information support of scientific researches – Current Research Information System as a part of the corporate information system. The objectives of such a system are focused on ensuring an effective implementation and research by using the modern information technology, computer technology and automation, creation, development and integration of digital resources on a common conceptual framework. The project assumes continuous system development, introduction the new information technologies to ensure the technological system relevance.

One of the main tasks of the NICA/MPD physics program is a study of low-mass vector mesons ρ, ω, ϕ by measuring their dileptonic decay channels. In this paper, the current status of simulations of electron-positron pair measurements in MPD is presented and the detector performance for such measurements is discussed.

A method for cluster recognition from nucleon distributions generated in calculations of relativistic collisions of light particles (protons, α-particles) with nuclei in the framework of the UrQMD model is proposed. The excitation energy of the clusters which is necessary to take into account the de-excitation of the calculated fragments, was estimated from empirical considerations. The approach was applied to calculate mass distributions of fragments in p + Fe collisions for different proton energies and showed a good correspondence to experimental results. The software implementation of the clustering method and a visualization of cluster formation substantially facilitate applications of the proposed method.

The development of the NICA/MPD project at JINR, which gives new prospects for heavy ion collisions and spin physics, is presented. The currently foreseen detector system, physics observables of interest, and feasibility studies of their measurement is presented.

Starting with a realistic quark model of nucleon structure, in which quarks are strongly correlated with one another within the nucleon, the light nuclei 2H, 3H, 3He, and 4He can be constructed by assuming similar correlations with the quarks in neighboring nucleons. Importance of color loops created owing to the closure of quark ends of adjacent nucleons is emphasized. Applying the model to larger nucleon systems reveals the emergence of symmetries at the nuclear level that are isomorphic with those known from the independent-particle (shell) model.

The cross sections for (d, xn), (d, pxn), (p, xn), and (p, pxn) reactions on enriched tin isotopes are obtained at a projectile energy of 3.65 GeV per nucleon. The yields in the energy range 0.66–8.1 GeV are analyzed with resort to experimental data obtained previously. Experimental data are compared with the results of theoretical calculations performed within the cascade-evaporation model. The dependence of the yields on the number of emitted neutrons, the projectile type, and the isotopic composition of a target is investigated. The cross sections for the (p, xpyn) reactions on a 120Sn target are presented at a primary-proton energy of 0.66 GeV.

A dynamical quark model of hadron and nucleus structure is proposed. It is shown in the framework of the model, called the Strongly Correlated Quark Model, that quarks and nucleons inside nuclei are arranged in crystal–like structure.

Analysis of isotopic characteristics of products related to the inclusive data measured using activation method in proton reactions at the energies 0.66, 1.0 and 8.1 GeV with separated tin isotopes is presented. Experimental results are systematized in form of cross section ratios for two targets of different isotope composition. Scaling behavior is observed for reactions with heavy residuals in the same manner as in light fragment production processes. These results are discussed in the light of relevant recent data. Finally, dependence of scaling parameters on the target neutron excess is observed.

In proton-nucleus reactions, the ratios of the cross sections for 18 isomeric pairs were measured by the induced-activity method as functions of the initial-proton energy and of the number of emitted nucleons. The isotopic effect and the cross sections for charge-exchange reactions are discussed. The experimental values of the cross sections for disintegration reactions like (p, xpyn) are compared with the theoretical values calculated on the basis of the cascade-evaporation model.

The mechanism of formation of residual nuclei in the mass region 42≤A≤81 in the reactions of protons with separated tin isotopes at three protons energies 0.66, 1.0 and 8.1 GeV was investigated. The absolute cross-sections of the residual nuclei were compared with the theoretical ones calculated by the standard cascade-evaporation and the intranuclear cascad plus statistical multifragmentation models (INC + SMM). It was shown that at E p =8.1 GeV these nuclei may arise both from disintegration of the nucleus and as partners of several fragments.

The interplay between hard and soft interactions is interpreted in the frame of the model where the motion of valence quarks inside a hadron represents a strongly correlated classical oscillators. Connection of the model considerations with Casimir effect is discussed.

It is shown that the rise of total cross sections in hadron – proton collisions can be explained by spatial features of hadronic matter distributions and kinematical factors.

In the framework of the proposed by the author Strongly Correlated Quark Model the valence quarks are treated as vortical solitons, and the proton spin arises from the additive sum of the valence quark vorticities. The spin "crisis" is a manifestation of the irrotational character of vortical fields quarks.

The Single Transverse — Spin Asymmetry (SSA) is analysed in the framework of the Strongly Correlated Quark Model proposed by author, where the proton spin emerges from the orbital momenta of quark and qluon condensates circulating around the valence quarks. It is shown that dominating factors of appearance of SSA are the orbiting around the valence quarks sea quark and qluon condensates and spin dependent quark‐quark cross sections.

Starting with a realistic quark model of nucleon structure, in which quarks are strongly correlated with one another within the nucleon, the smallest nuclei, 2He, 3H, 3He and 4He can be constructed by assuming similar correlations with the quarks in neighboring nucleons. Importance of color loops created owing to the closure of quark ends of adjacent nucleons is emphasized. Applying the model to larger nucleon systems reveals the emergence of symmetries at the nuclear level that are isomorphic with those known from the independent‐particle (shell) model.

A dynamical quark model of hadron and nucleus structure is proposed. In the framework of the model, called the Strongly Correlated Quark Model, quarks and nucleons inside nuclei are arranged in crystal‐like structure.

Multiparticle production in high energy proton -- proton collisions has been analysed in the frame of Strongly Correlated Quark Model (SCQM) of the hadron structure elaborated by the author. It is shown that inelasticity decreases at high energies and this effect together with the total cross section growth and the increasing with collision energy the masses of intermediate clusters result in the violation of KNO -- scaling., Comment: 21 pages, 11 figures, submitted to Yad. Fisika

It is shown, in the frame of the model proposed by author, that spin of the proton could be described by the orbital momentum of quark and qluon condensate circulating around valence quarks.

The process of nuclear multifragmentation has been implemented, together with evaporation and fission channels of the disintegration of excited remnants in nucleus-nucleus collisions using percolation theory and the intranuclear cascade model. Colliding nuclei are treated as face--centered--cubic lattices with nucleons occupying the nodes of the lattice. The site--bond percolation model is used. The code can be applied for calculation of the fragmentation of nuclei in spallation and multifragmentation reactions., Comment: 19 pages, 10 figures

Despite the many successes of QCD much of low energy hadronic physics cannot be extracted from the first principles of the theory. Quarks were first postulated as constituents of hadrons with masses about hundreds of MeV to describe the spectroscopy of hadrons. Subsequently, it was realized that hard processes are the arena of current quark considerations with masses much lighter than the original constituent ones. Relationship between current and constituent quarks is still smooth and unclear. According to the modern picture of hadrons quark-antiquark in mesons and three valence quarks in nucleons are dressed with gluons and ”sea” quark-antiquark pairs in such a way that they become much heavier, although the dynamical mechanism of dressing is not understood definitely.