Recently,a relativistic chiral nucleon-nucleon interaction was formulated up to leading order,which provides a good description of the phase shifts of J≤1 partial waves[Chin.Phys.C 42(2018)014103].Nevertheless,a separable regulator function that is not manifestly covariant was used in solving the relativistic scattering equation.In the present work,we first explore a covariant and separable form factor to regularize the kernel potential and then apply it to study the simplest but most challenging ^(1)S_(0) channel which features several lowenergy scales.In addition to being self-consistent,we show that the resulting relativistic potential can describe quite well the unique features of the ^(1)S_(0) channel at leading order,in particular the pole position of the virtual bound state and the zero amplitude at the scattering momentum ~340 MeV,indicating that the relativistic formulation may be more natural from the viewpoint of effective field theories.
Motivated by the successes of relativistic theories in studies of atomic/molecular and nuclear systems and the need for a relativistic chiral force in relativistic nuclear structure studies, we explore a new relativistic scheme to construct the nucleon-nucleon interaction in the framework of covariant chiral effective field theory. The chiral interaction is formulated up to leading order with covariant power counting and a Lorentz invariant chiral Lagrangian.We find that the relativistic scheme induces all six spin operators needed to describe the nuclear force. A detailed investigation of the partial wave potentials shows a better description of the;S——0 and;P;phase shifts than the leading order Weinberg approach, and similar to that of the next-to-leading order Weinberg approach. For the other partial waves with angular momenta J≥1, the relativistic results are almost the same as their leading order non-relativistic counterparts.
The N = 28 shell gap in sulfur, argon, calcium and titanium isotopes is investigated in the framework of relativistic continuum Hartree-Bogoliubov （RCHB） theory. The evolutions of neutron shell gap, separation energy, single particle energy and pairing energy are analyzed, and it is found that the N = 28 shell gap is quenched in sulfur isotopes but persists in argon, calcium and titanium isotopes. The evolution of the N = 28 shell gap in the N = 28 isotonic chain is discussed, and the erosion of the N = 28 shell gap is understood with the evolution of potential with proton number.
Single particles moving in a reflection-asymmetric potential are investigated by solving the Schr6dinger equation of the reflectionasymmetric Nilsson Hamiltonian with the imaginary time method in 3D lattice space and the harmonic oscillator basis expansion method. In the 3D lattice calculation, the l2 divergence problem is avoided by introducing a damping function, and the（l2）N term in the non-spherical case is calculated by introducing an equivalent N-independent operator. The efficiency of these numerical techniques is demonstrated by solving the spherical Nilsson Hamiltonian in 3D lattice space. The evolution of the single-particle levels in a reflection-asvmmetric ootential is obtained and discussed bv the above two numerical methods, and their consistencv is shown in the obtained single-particle energies with the differences smaller than 10-4[hω0]
Mass is a fundamental property and an important fingerprint of atomic nucleus.It provides an extremely useful test ground for nuclear models and is crucial to understand energy generation in stars as well as the heavy elements synthesized in stellar explosions.Nuclear physicists have been attempting at developing a precise,reliable,and predictive nuclear model that is suitable for the whole nuclear chart,while this still remains a great challenge even in recent days.Here we employ the Fourier spectral analysis to examine the deviations of nuclear mass predictions to the experimental data and to present a novel way for accurate nuclear mass predictions.In this analysis,we map the mass deviations from the space of nucleon number to its conjugate space of frequency,and are able to pin down the main contributions to the model deficiencies.By using the radial basis function approach we can further isolate and quantify the sources.Taking a pedagogical mass model as an example,we examine explicitly the correlation between nuclear effective interactions and the distributions of mass deviations in the frequency domain.The method presented in this work,therefore,opens up a new way for improving the nuclear mass predictions towards a hundred kilo-electron-volt accuracy,which is argued to be the chaos-related limit for the nuclear mass predictions.
The α-decay energies （Qα） are systematically investigated with the nuclear masses for 10 ≤Z ≤120 isotopes obtained by the relativistic continuum Hartree-Bogoliubov （RCHB） theory with the covariant density func- tional PC-PK1, and compared with available experimental values. It is found that the α-decay energies deduced from the RCHB results present a similar pattern to those from available experiments. Owing to the large predicted Qα values （≥4 MeV）, many undiscovered heavy nuclei in the proton-rich side and super-heavy nuclei may have large possibilities for α-decay. The influence of nuclear shell structure on α-decay energies is also analysed.
The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spectra,electromagnetic transition probabilities B（M1） and B（E2）,angular momenta,and K-distributions are studied.It is demonstrated that the chirality still remains not only in the yrast and yrare bands,but also in the two higher excited bands whenγ deviates from 30°.The chiral geometry relies significantly on γ,and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands.
