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[en] Part I: The Covariant Spectator approach for two and three nucleon interactions at JLab energies. Part II: Ideas for improvements--toward a Covariant Effective field theory for GeV reactions

[en] In this talk I will address the feasibility and desirability of building a theory of nuclei around nucleon-nucleon potentials defined on the light front. 11 refs

[en] Recently many studies have been devoted for understanding the nucleon-nucleon interaction and the atomic nuclei structure starting from quark models. The way for this problem solution selected by us is based on a nontraditional consideration of the confinement of valence quarks in cases when two, three or more nucleons approach each other and the corresponding confinement potentials come into contact and vanish. The overlap of wave-functions of valence quarks, trapped in different nucleons, causes correlations thus giving the possibility to understand the peculiarities of the nucleon-nucleon interaction and corresponding potential modifications in case, when interacting nucleons are present in atomic nucleus. The investigated systems of double-, triple- and larger number of confining harmonic oscillator wells opens new possibilities for recent realistic nucleon-nucleon potentials modifications taking into account the substructure of interacting nucleons. Nucleons entering the interaction area change due to the intrinsic structure modification. These changes are dependent on the presence of ''spectator'' nucleons in vicinity of interacting ones. This observation can serve as alternative of three nucleon potential necessary for lightest nuclei description.

[en] This is a survey of recent progress in the construction of a realistic nucleon-nucleon potential in which the degrees of freedom of mesons and isobars are taken into account as completely and as carefully as possible. Predictions on the three body systems as well as nuclear matter are also reported

[en] The technique of the effective range expansion is commonly used in nucleon-nucleon scattering to encode the properties of the nuclear force in a small set of parameters. However, the applicability of the effective range expansion is limited by the longest-range part of the nuclear potential, i.e. by the one pion exchange, to the domain of momenta below half the pion mass. In the 1960s the formalism of the modified effective range expansion was developed. It was first used to remove the effects of the Coulomb force to study proton-proton scattering. We apply this formulation to the nucleon-nucleon interaction to separate the known long-range interactions from the rest to be able to go beyond the momentum region described above. To show the effectiveness of this technique, we consider a toy model with a two-range potential and study the behaviour of the parameters of the effective and modified effective range expansion in this two-scale problem.

[en] More caution is necessary when claiming isobar effects than had hitherto been thought necessary. This has resulted in improved versions for the transition potentials that generate isobar configurations from purely nucleonic configurations, as is described in section 2. In section 3 the thorny problem of crossed-pion processes involving isobars is briefly mentioned. In section 4 some recent applications with isobar configurations are given. (orig./AH)

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[en] We systematically study the NN→baryon+baryon quark-exchange terms. The effective numbers for the different baryon-baryon components in the deuteron are calculated

No abstract available