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Momentum and density dependence of single-nucleon potential u ( k, ρ, β) is analyzed using a density dependent finite range effective interaction of the Yukawa form. Depending on the choice of the strength parameters of exchange interaction, two different trends of the momentum dependence of nuclear symmetry potential are noticed which lead to two opposite types of neutron and proton effective mass splitting. The 2nd-order and 4th-order symmetry energy of isospin asymmetric nuclear matter are expressed analytically in terms of the single-nucleon potential. Two distinct behavior of the density dependence of 2nd-order and 4th-order symmetry energy are observed depending on neutron and proton effective mass splitting. It is also found that the 4th-order symmetry energy has a significant contribution towards the proton fraction of β-stable npeμ matter at high densities. [ABSTRACT FROM AUTHOR]

The odd–odd nucleus 30 Na is studied via a one-proton, one-proton–one-neutron and one-neutron removal reaction using an intermediate-energy 31 Mg, 32 Mg and 31 Na radioactive ion beam, respectively. Combining high-resolution γ -ray spectroscopy with the selectivity of the three reaction mechanisms, we are able to distinguish multiple particle–hole configurations. Negative-parity states in 30 Na are observed for the first time, providing an important measure of the excitation of the 1p1h/3p3h configuration and hence the sd – pf shell gap. The extracted band structures and level energies serve as invaluable input for the theoretical refinement of the effective interactions used in this region. [ABSTRACT FROM AUTHOR]

Abstract: Effective interactions can be obtained from a renormalization group analysis in two complementary ways. One can either explicitly integrate out higher energy modes or impose given conditions at low energies for a cut-off theory. While the first method is numerically involved, the second one can be solved almost analytically. In both cases we compare the outcoming effective interactions for the two nucleon system as functions of the cut-off scale and find a strikingly wide energy region where both approaches overlap, corresponding to relevant scales in light nuclei . This amounts to a great simplification in the determination of the effective interaction parameters. [Copyright &y& Elsevier]

We report on the first observation of dineutron emission in the decay of 16Be. A single-proton knockout reaction from a 53 MeV/u 16B beam was used to populate the ground state of 16Be. 16Be is bound with respect to the emission of one neutron and unbound to two-neutron emission. The dineutron character of the decay is evidenced by a small emission angle between the two neutrons. The two-neutron separation energy of 16Be was measured to be 1.35(10) MeV, in good agreement with shell model calculations, using standard interactions for this mass region. [ABSTRACT FROM AUTHOR]

We study the scaling of the localization length of two interacting bosons in a one-dimensional random lattice with the single particle localization length. We consider the short-range interaction assuming that the particles interact when located both on the same site. We discuss several regimes, among them one interesting weak Fock space disorder regime. In this regime we obtain a weak logarithmic scaling law. Numerical benchmark data support the absence of any strong enhancement of the two particle localization length. [ABSTRACT FROM AUTHOR]

The ground state properties of light closed shell nuclei, i.e. 4He, 12C, 16O, 28Si, 32S, 40Ca and 56Ni are studied by using the channel-dependent effective two-body interactions (CDEI's). The CDEI's are generated through the lowest-order constrained variational (LOCV) calculation for asymmetric nuclear matter with the charge-dependent Av18 bare nucleon-nucleon potential. The work is performed on the harmonic oscillator basis, and the local density approximation is applied to create the relative and the center of mass dependent effective two-body potential. Unlike nuclear matter, and similar to our previous calculations with the Reid68 interaction, while the Av18 potential under binds above nuclei up Jmax = 2 channel, it gives ground state binding energies closer to the experimental data with respect to the Δ- Reid68 and the Reid68 potentials. There are not much difference between the results of Av18 interaction with Jmax = 5, and those of Reid68Day potential which has been define up to Jmax = 5. The different CDEI's up to Jmax = 5 are discussed and the results of our calculations are compared with the other theoretical approaches and experimental data. Finally, it is shown that the contributions of higher partial waves (J>2) are not very important and the two-body kinetic energy in J = 1 channel is roughly twice as that of J = 0 which is not the case for the two-body potential energy. [ABSTRACT FROM AUTHOR]

Abstract: A review is presented of the development and current status of nuclear shell-model calculations, in which the two-body effective interaction between valence nucleons is derived from the free nucleon–nucleon potential. The significant progress made in this field within the last decade is emphasized, in particular as regards the so-called approach to the renormalization of the bare nucleon–nucleon interaction. In the last part of the review, we first give a survey of realistic shell-model calculations from early to present days. Then, we report recent results for neutron-rich nuclei near doubly magic 132Sn, and for the whole even-mass isotonic chain. These illustrate how shell-model effective interactions derived from modern nucleon–nucleon potentials are able to provide an accurate description of nuclear structure properties. [Copyright &y& Elsevier]

Effective interactions and transition operators have a long history in nuclear physics. From the early works of Brueckner and Bethe to the present time, microscopic approaches based on realistic nucleon–nucleon interactions, fit to phase shifts, have produced many useful results and insights. Recently, an ab initio approach has been developed that successfully weds a no-core finite basis state treatment, conserving center of mass motion, with an Hermitian effective Hamiltonian derived from realistic two-nucleon and tri-nucleon interactions. We present this approach with a sample of recent results. [ABSTRACT FROM AUTHOR]

We present a brief overview of microscopic nuclear structure approaches to nuclei with A∼ 100–132. The emphasis is on the shell model and theories for deriving effective interactions starting from the free interactions between nucleons. New results for 105,106,107Sb are presented. [Copyright &y& Elsevier]

The article explains why the configuration interaction expansion is the correct solution of the electronic Schrödinger equation. Mostly developed during the 20th century, quantum theory is considered a powerful tool that explains the behavior of nature at the microscopic level. This is true since one of its postulates stresses that the knowledge of the wave function, the solution of the Schrödinger equation, provides a complete determination of the state of a system. However, it is an extremely difficult task that requires enormous computational effort to calculate the exact solution of the Schrödinger equation.