Search

A detailed analysis is made of the pair, ρπγ-currents, retardation effects and six-quark admixtures to the charge, quadrupole form factors and to the deuteron polarization. It is shown that the elastic eD-scattering cross section allowing for the meson exchange currents can be described by introducing a six-quark admixture with probability 3.5%. It is predicted that the behaviour of the deuteron polarization tensor at q>4 fm essentially depends on 6q-admixture. [ABSTRACT FROM AUTHOR]

The model of orthogonal coupled channels is carried out for the NN interaction and the description of electromagnetic processes in two-nucleon system. Both the adequate reflection of the six-quark dynamics in the region of nucleon overlap and mesonic physics at middle and long ranges is attained in the given model. The processes of elastic and inelastic magnetic scattering of electrons on deuteron are investigated and compared with traditional description on the basis of the potentials with a repulsive core. [ABSTRACT FROM AUTHOR]

Several nucleon form factors are computed within the framework of the linear chiral soliton model. To this end variational means and projection techniques applied to generalized hedgehog quark-boson Fock states are used. In this procedure the Goldberger-Treiman relation and a virial theorem for the pion-nucleon form factor are well fulfilled demonstrating the consistency of the treatment. Both proton and neutron charge form factors are correctly reproduced, as well as the proton magnetic one. The shapes of the neutron magnetic and of the axial form factors are good but their absolute values at the origin are too large. The slopes of all the form factors at zero momentum transfer are in good agreement with the experimental data. The pion-nucleon form factor exhibits to great extent a monopole shape with a cut-off mass of Λ=690 MeV. Electromagnetic form factors for the vertex γNΔ and the nucleon spin distribution are also evaluated and discussed. [ABSTRACT FROM AUTHOR]

We investigate the incorporation of condensates in Light Cone quantisation in the frame-work of the Nambu-Jona-Lasinio model. Although it is shown that the physical and perturbative vacua are identical, a gap equation for the dynamical quark mass is obtained and chiral symmetry is dynamically broken. The complete fermion condensate is found in the perturbative vacuum. The corresponding Goldstone mode is a zero mass bound state of the Weinberg equation. [ABSTRACT FROM AUTHOR]

We investigate the Skyrme type soliton with vector mesons (ρ, A and ω), first in the massive Yang-Mills approach and then using the hidden local symmetry Lagrangian. It is demonstrated that the two schemes give identical results for the soliton properties. A comparison is made with alternative approaches in which the A degrees of freedom is eliminated. [ABSTRACT FROM AUTHOR]

We show that the dinotor is sensitive to discrete energy level corrections to the continuum approximation for the density of states. These corrections do not destroy the metastability of the dinotor, but may produce a 'magic number' effect. New metastable configurations of the dinotor may also exist, possibly creating further difficulty identifying the dinotor as the cause of the anomalon effect. [ABSTRACT FROM AUTHOR]

The Roper excitation is studied in the chiral bag plus skyrmion hybrid model. The lagrangian is expanded around the classical solution in the hedgehog vibrational mode. In the adiabatic approximation we find a self consistent solution for the fluctuating system of quarks and pions up to the first order of the fluctuations. Only half of the excitation energy was found in the phase shift analysis. It is also discussed that the system is stable for all bag radii against the hedgehog vibration. [ABSTRACT FROM AUTHOR]

We study the dynamics generated by local gauge invariance under a non-abelian SU(N) group for two nonrelativistic particles interacting through the effect of the group charges. We describe the local gauge invariant potential which contains the exchange of infinitely many gluons. We discuss the possible implications of our result. [ABSTRACT FROM AUTHOR]

The linear chiral soliton model is solved for nucleon and delta by constructing Fock states in the coherent pair approximation with correct spin and isospin properties. The quark configurations are those arising from the SU(2)× SU(2) coupling of three quarks in 1 s-orbits. The overall Fock state is formed by the vector coupling of the quark configurations with the pion coherent state and thus avoids the use of the hedgehog ansatz. The sigma field is treated in the mean field approximation. Equations of motion for the quark, sigma and pion fields are solved in the static approximation. Soliton solutions are found with properties that are in reasonable agreement with those observed for the nucleon and delta including the axial vector coupling constant. With only components having zero and one unpaired pion in the coherent pair approximation the nucleon mass is found to be larger than that using the projected hedgehog approach. [ABSTRACT FROM AUTHOR]

Model calculations for nuclear properties such as shell structure, magnetic moments and charge distributions are presented where quarks instead of nucleons are used as the fundamental nuclear constituents. It is shown that such a new picture is able to reproduce the gross properties of the classical theory. Nucleons and nuclear Δ-resonances show, however, a partial quark deconfinemement which leads to Pauli-blocking. [ABSTRACT FROM AUTHOR]

The low energy nucleon-nucleon system is analyzed by means of a model interaction which includes coupling of the nucleons to an 'elementary deuteron' state. The probability of the elementary particle component, or 'elementarity', of the physical deuteron is investigated. It is found that, contrary to earlier assertions, the low energy scattering parameters do not determine the elementarity of the deuteron in a model-independent way. [ABSTRACT FROM AUTHOR]

A relativistic version of the P model is proposed. We adopt a bag model and assume that a q $$\bar q$$ pair is connected with a Coulomb type gluon. The strong interaction vertices of ρ→ π π and meson-nucleon couplings are explained consistently by a parameter γ, which specifies the strength of the q $$\bar q$$ pair creation and annihilation vertices. [ABSTRACT FROM AUTHOR]

The probability of the six-quark bag part of the deuteron is defined within recently formulated quark compound bag (QCB) model. An upper limit of about 1 % for the admixture of the confined bag in the deuteron is found for the QCB potential supplied by the long range Paris interaction. The six-quark bag corrections to the static multipole moments of the deuteron are estimated to be ≲1 % for μ and ≲6% for Q. [ABSTRACT FROM AUTHOR]