arXiv subjects

Nir Barnea

Publications and source records attributed to Nir Barnea.

95 records · Page 6Linked to original sources

arXiv1999

State Dependent Effective Interaction for the Hyperspherical Formalism

The method of effective interaction, traditionally used in the framework of an harmonic oscillator basis, is applied to the hyperspherical formalism of few-body nuclei (A=3-6). The separation of the hyperradial part leads to a state dependent effective potential. Undesirable features of the harmonic oscillator approach associated with the introduction of a spurious confining potential are avoided. It is shown that with the present method one obtains an enormous improvement of the convergence of the hyperspherical harmonics series in calculating ground state properties, excitation energies and transitions to continuum states.

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arXiv1999

Nuclear Matter with Quark-Meson Coupling I: Comparison of Nontopological Soliton Models

A system of nontopological solitons interacting through scalar and vector meson exchange is used to model nuclear matter. The models studied are of the Friedberg-Lee type, which exhibit dynamical bag formation due to the coupling of quarks to a scalar composite gluon field. It is shown that the chiral chromodielectric model gives the best fit to the empirical data. The presence of the scalar meson guarantees saturation and an increase of the proton charge radius with nuclear density consistent with the EMC effect.

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arXiv1999

Nuclear Matter with Quark-Meson Coupling II: Modeling a Soliton Liquid

We study in further detail a nontopological soliton model with coupling between quarks and mesons selected as promising in the previous work. Here we go beyond the Wigner-Seitz approximation by introducing the disorder necessary to reproduce the liquid state. We study nuclear matter, with particular interest in the transition to a quark-gluon plasma. The model studied is a variation of the chiral chromodielectric model of Fai, Perry and Wilets, where explicit coupling to a scalar meson field is introduced.

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arXiv1998

Ground State Wave Functions in the Hyperspherical Formalism for Nuclei with A > 4

The general formulation of a technically advantageous method to find the ground state solution of the Schrodinger equation in configuration space for systems with a number of particles A greater than 4 is presented. The wave function is expanded in pair correlated hyperspherical harmonics beyond the lowest order approximation and then calculated in the Faddeev approach. A recent efficient recursive method to construct antisymmetric A-particle hyperspherical harmonics is used. The accuracy is tested for the bound state energies of nuclei with A = 6,8,12. The high quality of the obtained results becomes evident from a comparison with other approaches.

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arXiv1997

S-wave Pairing of $Λ$ Hyperons in Dense Matter

In this work we calculate the $^1S_0$ gap energies of $Λ$ hyperons in neutron star matter. The calculation is based on a solution of the BCS gap equation for an effective G-matrix parameterization of the $Λ-Λ$ interaction with a nuclear matter background, presented recently by Lanskoy and Yamamoto. We find that a gap energy of a few tenths of MeV is expected for $Λ$ Fermi momenta up to about 1.3 fm$^{-1}$. Implications for neutron star matter are examined, and suggest the existence of a $Λ$ $^1S_0$ superfluid between the threshold baryon density for $Λ$ formation and the baryon density where the $Λ$ fraction reaches $15-20%$.

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