Nonrelativistic Mean-field Theory Research Articles

Parameter-independent predictions for nuclear shapes and B(E2) transition rates in the proxy-SU(3) model

Using a new approximate analytic parameter-free proxy-SU(3) scheme, we make predictions of shape observables for actinides and superheavy elements, namely β and γ deformation variables, and compare these with predictions by relativistic and non-relativistic mean-field theories. Furthermore, we make predictions for B(E2) transition rates of deformed nuclei and compare these with existing data and predictions of other theoretical approaches.

Neutron–proton effective mass splitting and thermal evolution in neutron-rich matter

The thermal evolution of properties of neutron-rich asymmetric nuclear matter such as entropy density, internal energy density, free energy density and pressure is studied in the non-relativistic mean field theory using finite range effective interactions. In this framework, the thermal evolution of nuclear matter properties is directly connected to the neutron and proton effective mass properties. Depending on the magnitude of neutron–proton effective mass splittings, two distinct behaviours in the thermal evolution of nuclear matter properties are noticed.

Temperature dependence of the nuclear symmetry energy and equation of state of charge neutral n + p + e + μ matter in beta equilibrium

The temperature and density dependence of the nuclear symmetry energy is studied in the nonrelativistic mean field theory by using a density-dependent finite range effective interaction. The temperature evolution of the interaction part of symmetry energy is decided by the nature of the finite range exchange interactions acting between a pair of like and unlike nucleons, an area which is less understood. In view of this, two cases corresponding to different strengths of exchange interaction between two like nucleons are considered to examine their influence on the temperature dependence of the nuclear symmetry energy. The symmetry energy obtained as a function of temperature and density is used to study the temperature dependence of leptonic fractions, proton fraction and equation of state of charge neutral n + p + e + μ matter under β-equilibrium for the two different cases.

Central depression in nuclear density and its consequences for the shell structure of superheavy nuclei

IKH, Research Center Rossendorf, Dresden, Germany(Dated: February 9, 2008)The influence of the central depression in the density distribution of spherical superheavy nucleion the shell structure is studied within the relativistic mean field theory. Large depression leadsto the shell gaps at the proton Z = 120 and neutron N = 172 numbers, while flatter densitydistribution favors N = 184 for neutrons and leads to the appearance of a Z = 126 shell gap andto the decrease of the size of the Z = 120 shell gap. The correlations between the magic shell gapsand the magnitude of central depression are discussed for relativistic and non-relativistic mean fieldtheories.

Single-particle and collective motion for proton-rich nuclei in the upperpfshell

Based on available experimental data, a new set of Nilsson parameters is proposed for proton-rich nuclei with proton or neutron numbers $28<~N<~40.$ The resulting single-particle spectra are compared with those from relativistic and nonrelativistic mean field theories. Collective excitations in some even-even proton-rich nuclei in the upper $\mathrm{pf}$ shell are investigated using the projected shell model with the new Nilsson basis. It is found that the regular bands are sharply disturbed by band crossings involving ${1g}_{9/2}$ neutrons and protons. Physical quantities for exploring the nature of the band disturbance and the role of the ${1g}_{9/2}$ single-particle are predicted, which may be tested by new experiments with radioactive beams.

Superdeformations in relativistic and non-relativistic mean field theories

The applications of the extensions of relativistic mean field (RMF) theory to the rotating frame, such as cranked relativistic mean field (CRMF) theory and cranked relativistic Hartree-Bogoliubov (CRHB) theory, for the description of superdeformed bands in the A ∼ 60, 140 – 150 and 190 mass regions are overviewed and compared briefly with the results obtained in non-relativistic mean field theories.

Relativistic Quantum Electrodynamics of Atoms

Relativistic and non-relativistic mean-field theories are discussed in the framework of quantum electrodynamics. g-Hartree mean-fields are derived using methods of the steepest descent which yields semi-classical expansions as a generalisation of asymptotic expansions of classical analysis. Our applications of the g-Hartree theory of atoms show that, in the examples considered, correlations are efficiently suppressed.

On the relation between relativistic and non-relativistic mean-field theories

It is shown that the relativistic mean-field theories (Dirac-Hartree approximation) based on one-boson exchange potentials can also be interpreted in more traditional terms, in the case of nuclear ground states. This requires the use of velocity-dependent two-body forces (of Skyrme type, in the limit of large meson masses), and application of the Lorentz-Lorenz correction.