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The nucleon-nucleon interaction and properties of the nucleon in a $pirhoomega$ soliton model including a dilaton field with anomalous dimension

68   0   0.0 ( 0 )
 Added by Abdulla Rakhimov
 Publication date 1999
  fields
and research's language is English




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We investigate an extended chiral soliton model which includes $pi, rho, omega$ and $sigma $ mesons as explicit degrees of freedom. The Lagrangian incorporates chiral symmetry and broken scale invariance. A scalar-isoscalar meson $sigma$ is associated with a quarkonium dilaton field with a mass $msigapprox 550 $MeV. We show that the scalar field with anomalous dimension slightly changes the static and electromagnetic properties of the nucleon. In contrast, it plays a significant role in nucleon-nucleon dynamics and gives an opportunity to describe well the two-nucleon interaction.



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We upgrade a SU_6 quark-model description for the nucleon-nucleon and hyperon-nucleon interactions by improving the effective meson-exchange potentials acting between quarks. For the scalar- and vector-meson exchanges, the momentum-dependent higher-order term is incorporated to reduce the attractive effect of the central interaction at higher energies. The single-particle potentials of the nucleon and Lambda, predicted by the G-matrix calculation, now have proper repulsive behavior in the momentum region q_1=5 - 20 fm^-1. A moderate contribution of the spin-orbit interaction from the scalar-meson exchange is also included. As to the vector mesons, a dominant contribution is the quadratic spin-orbit force generated from the rho-meson exchange. The nucleon-nucleon phase shifts at the non-relativistic energies up to T_lab=350 MeV are greatly improved especially for the 3E states. The low-energy observables of the nucleon-nucleon and the hyperon-nucleon interactions are also reexamined. The isospin symmetry breaking and the Coulomb effect are properly incorporated in the particle basis. The essential feature of the Lambda N - Sigma N coupling is qualitatively similar to that obtained from the previous models. The nuclear saturation properties and the single-particle potentials of the nucleon, Lambda and Sigma are reexamined through the G-matrix calculation. The single-particle potential of the Sigma hyperon is weakly repulsive in symmetric nuclear matter. The single-particle spin-orbit strength for the Lambda particle is very small, in comparison with that of the nucleons, due to the strong antisymmetric spin-orbit force generated from the Fermi-Breit interaction.
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