Tamara Nikšić

Relativistic Hartree-Bogoliubov model with density-dependent meson-nucleon couplings

The relativistic Hartree-Bogoliubov (RHB) model is extended to include density-dependent meson-nucleon couplings. The effective Lagrangian is characterized by a phenomenological density dependence of the

Relativistic Nuclear Energy Density Functionals: Mean-Field and Beyond

\ensuremath{\sigma},

Relativistic Nuclear Energy Density Functionals: Adjusting parameters to binding energies

\ensuremath{\omega},

Quasiparticle random phase approximation based on the relativistic Hartree-Bogoliubov model

and

Beyond the relativistic mean-field approximation. III. Collective Hamiltonian in five dimensions

\ensuremath{\rho}

Quasiparticle random phase approximation based on the relativistic Hartree-Bogoliubov model. II. Nuclear spin and isospin excitations

meson-nucleon vertex functions, adjusted to properties of nuclear matter and finite nuclei. Pairing correlations are described by the pairing part of the finite range Gogny interaction. The new density-dependent effective interaction DD-ME1 is tested in the analysis of the equations of state for symmetric and asymmetric nuclear matter, and of ground-state properties of the Sn and Pb isotopic chains. Results of self-consistent RHB calculations are compared with experimental data, and with results previously obtained in the RHB model with nonlinear self-interactions, as well as in the density-dependent relativistic hadron field (DDRH) model. Parity-violating elastic electron scattering on Pb and Sn nuclei is calculated using a relativistic optical model with inclusion of Coulomb distortion effects, and the resulting asymmetry parameters are related to the neutron ground-state density distributions.

Microscopic Description of Nuclear Quantum Phase Transitions

Relativistic energy density functionals (EDF) have become a standard tool for nuclear structure calculations, providing a complete and accurate, global description of nuclear ground states and collective excitations. Guided by the medium dependence of the microscopic nucleon self-energies in nuclear matter, semi-empirical functionals have been adjusted to the nuclear matter equation of state and to bulk properties of finite nuclei, and applied to studies of arbitrarily heavy nuclei, exotic nuclei far from stability, and even systems at the nucleon drip-lines. REDF-based structure models have also been developed that go beyond the static mean-field approximation, and include collective correlations related to the restoration of broken symmetries and to fluctuations of collective variables. These models are employed in analyses of structure phenomena related to shell evolution, including detailed predictions of excitation spectra and electromagnetic transition rates.

Toroidal dipole resonances in the relativistic random phase approximation

The relativistic mean-field plus random phase and quasiparticle random phase approximation calculations, based on effective Lagrangians with density-dependent meson-nucleon vertex functions, are employed in a microscopic analysis of the nuclear matter compressibility and symmetry energy. We compute the isoscalar monopole response of 90Zr, 116Sn, 144Sm, the isoscalar monopole and isovector dipoles response of 208Pb, and also the differences between the neutron and proton radii for 208Pb and several Sn isotopes. The comparison of the calculated excitation energies with the experimental data on the giant monopole resonances restricts the nuclear matter compression modulus of structure models based on the relativistic mean-field approximation to Knm 250-270 MeV. The isovector giant dipole resonance in 208Pb and the available data on differences between the neutron and proton radii limit the range of the nuclear matter symmetry energy at saturation (volume asymmetry) of these effective interactions to 32 MeV < a4 < 36 MeV.

How atomic nuclei cluster

We study a particular class of relativistic nuclear energy density functionals in which only nucleon degrees of freedom are explicitly used in the construction of effective interaction terms. Short-distance (high-momentum) correlations, as well as intermediate- and long-range dynamics, are encoded in the medium (nucleon-density) dependence of the strength functionals of an effective interaction Lagrangian. Guided by the density dependence of microscopic nucleon self-energies in nuclear matter, a phenomenological ansatz for the density-dependent coupling functionals is accurately determined in self-consistent mean-field calculations of binding energies of a large set of axially deformed nuclei. The relationship between the nuclear matter volume, surface, and symmetry energies and the corresponding predictions for nuclear masses is analyzed in detail. The resulting best-fit parametrization of the nuclear energy density functional is further tested in calculations of properties of spherical and deformed medium-heavy and heavy nuclei, including binding energies, charge radii, deformation parameters, neutron skin thickness, and excitation energies of giant multipole resonances.