J. M. Yao

New parametrization for the nuclear covariant energy density functional with a point-coupling interaction

A new parametrization PC-PK1 for the nuclear covariant energy density functional with nonlinear point-coupling interaction is proposed by fitting to observables of 60 selected spherical nuclei, including the binding energies, charge radii, and empirical pairing gaps. The success of PC-PK1 is illustrated in the description of infinite nuclear matter and finite nuclei including the ground-state and low-lying excited states. In particular, PC-PK1 provides a good description for the isospin dependence of binding energy along either the isotopic or the isotonic chain, which makes it reliable for application in exotic nuclei. The predictive power of PC-PK1 is also illustrated for the nuclear low-lying excitation states in a five-dimensional collective Hamiltonian in which the parameters are determined by constrained calculations for triaxial shapes.

Configuration mixing of angular-momentum-projected triaxial relativistic mean-field wave functions

The framework of relativistic energy-density functionals is extended to include correlations related to the restoration of broken symmetries and to fluctuations of collective variables. The generator coordinate method is used to perform configuration mixing of angular-momentum-projected wave functions, generated by constrained self-consistent relativistic mean-field calculations for triaxial shapes. The effects of triaxial deformation and of K mixing is illustrated in a study of spectroscopic properties of low-spin states in {sup 24}Mg.

Configuration mixing of angular-momentum-projected triaxial relativistic mean-field wave functions. II. Microscopic analysis of low-lying states in magnesium isotopes

The recently developed structure model that uses the generator coordinate method to perform configuration mixing of angular-momentum projected wave functions, generated by constrained self-consistent relativistic mean-field calculations for triaxial shapes (3DAMP+GCM), is applied in a systematic study of ground states and low-energy collective states in the even-even magnesium isotopes 20–40Mg. Results obtained using a relativistic point-coupling nucleon-nucleon effective interaction in the particle-hole channel and a density-independent δ interaction in the pairing channel are compared to data and with previous axial 1DAMP+GCM calculations, both with a relativistic density functional and the nonrelativistic Gogny force. The effects of the inclusion of triaxial degrees of freedom on the low-energy spectra and E2 transitions of magnesium isotopes are examined.

Three-dimensional angular momentum projection in relativistic mean-field theory

Based on a relativistic mean-field theory with an effective point coupling between the nucleons, three-dimensional angular momentum projection is implemented for the first time to project out states with designed angular momentum from deformed intrinsic states generated by triaxial quadrupole constraints. The same effective parameter set PC-F1 of the effective interaction is used for deriving the mean field and the collective Hamiltonian. Pairing correlations are taken into account by the BCS method using both monopole forces and zero-range {delta} forces with strength parameters adjusted to experimental even-odd mass differences. The method is applied successfully to the isotopes {sup 24}Mg, {sup 30}Mg, and {sup 32}Mg.

Systematic study of nuclear matrix elements in neutrinoless double-

We report a systematic study of nuclear matrix elements (NMEs) in neutrinoless double-

\beta

\ensuremath{\beta}

decay with a beyond-mean-field covariant density functional theory

decays with a state-of-the-art beyond-mean-field covariant density functional theory. The dynamic effects of particle-number and angular-momentum conservations as well as quadrupole shape fluctuations are taken into account with projections and generator coordinate method for both initial and final nuclei. The full relativistic transition operator is adopted to calculate the NMEs. The present systematic studies show that in most of the cases there is a much better agreement with the previous nonrelativistic calculation based on the Gogny force than in the case of the nucleus

Time-odd triaxial relativistic mean field approach for nuclear magnetic moments

^{150}\mathrm{Nd}

Impurity effect of Lambda hyperon on collective excitations of nuclear core in MgΛ25

found by Song et al. [Phys. Rev. C 90, 054309 (2014)]. In particular, we find that the total NMEs can be well approximated by the pure axial-vector coupling term with a considerable reduction of the computational effort.

Beyond relativistic mean-field studies of low-lying states in neutron-deficient krypton isotopes

The time-odd triaxial relativistic mean field approach is developed and applied to the investigation of the ground-state properties of light odd-mass nuclei near the double-closed shells. The nuclear magnetic moments including the isoscalar and isovector ones are calculated, and good agreement with Schmidt values is obtained. Taking F-17 as an example, the splitting of the single-particle levels (around 0.7 MeV near the Fermi level), the nuclear current, the core polarizations, and the nuclear magnetic potential, i.e., the spatial part of the vector potential due to the violation of the time reversal invariance, are investigated in detail.