Charge radii of potassium isotopes in the RMF(BCS)* approach

We apply the recently proposed RMF(BCS)* ansatz to study the charge radii of the potassium isotopic chain up to $^{52}$K. It is shown that the experimental data can be reproduced rather well, qualitatively similar to the Fayans nuclear density functional theory, but with a slightly better description of the odd-even staggerings (OES). Nonetheless, both methods fail for $^{50}$K and to a lesser extent for $^{48,52}$K. It is shown that if these nuclei are deformed with a $beta_{20}approx-0.2$, then one can obtain results consistent with experiments for both charge radii and spin-parities. We argue that beyond mean field studies are needed to properly describe the charge radii of these three nuclei, particularly for $^{50}$K.

Quenching factor of Gamow-Teller and spin dipole giant resonances

Gamow-Teller (GT) and spin-dipole (SD) strength distributions of four doubly magic nuclei $^{48}$Ca, $^{90}$Zr, $^{132}$Sn and $^{208}$Pb are studied by the self-consistent Hartree-Fock plus random phase approximation (RPA) method. The Skyrme forces SAMi and SAMi-T without/with tensor interactions are adopted in our calculations. The calculated strengths are compared with available experimental data. The RPA results of GT and SD strengths of all four nuclei show fine agreement with observed GT and SD resonances in energy. A small GT peak below the main GT resonance is better described by the Skyrme interaction SAMi-T with the tensor terms. The quenching factors for GT and SD are extracted from the comparisons between RPA results and experimental strengths. It is pointed out that the quenching effect on experimental SD peaks is somewhat modest compared with that on GT peaks in the four nuclei.

Strangeness and $Delta$ resonance in compact stars with relativistic-mean-field models

We explore the effects of strangeness and $Delta$ resonance in baryonic matter and compact stars within the relativistic-mean-field (RMF) models. The covariant density functional PKDD is adopted for $N$-$N$ interaction, parameters fixed based on finite hypernuclei and neutron stars are taken for the hyperon-meson couplings, and the universal baryon-meson coupling scheme is adopted for the $Delta$-meson couplings. In light of the recent observations of GW170817 with the dimensionless combined tidal deformability $197 leq bar{Lambda}leq 720$, we find it is essential to include the $Delta$ resonances in compact stars, and small $Delta$-$rho$ coupling $g_{rho Delta}$ is favored if the mass $2.27{}_{-0.15}^{+0.17} M_odot$ of PSR J2215+5135 is confirmed.

Massive neutron stars and $Lambda$-hypernuclei in relativistic mean field models

Based on relativistic mean field (RMF) models, we study finite $Lambda$-hypernuclei and massive neutron stars. The effective $N$-$N$ interactions PK1 and TM1 are adopted, while the $N$-$Lambda$ interactions are constrained by reproducing the binding energy of $Lambda$-hyperon at $1s$ orbit of $^{40}_{Lambda}$Ca. It is found that the $Lambda$-meson couplings follow a simple relation, indicating a fixed $Lambda$ potential well for symmetric nuclear matter at saturation densities, i.e., around $V_{Lambda} = -29.786$ MeV. With those interactions, a large mass range of $Lambda$-hypernuclei can be well described. Furthermore, the masses of PSR J1614-2230 and PSR J0348+0432 can be attained adopting the $Lambda$-meson couplings $g_{sigmaLambda}/g_{sigma N}gtrsim 0.73$, $g_{omegaLambda}/g_{omega N}gtrsim 0.80$ for PK1 and $g_{sigmaLambda}/g_{sigma N}gtrsim 0.81$, $g_{omegaLambda}/g_{omega N}gtrsim 0.90$ for TM1, respectively. This resolves the Hyperon Puzzle without introducing any additional degrees of freedom.