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Register a new userCompressibility, effective mass and density dependence in Skyrme forces
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Generalized density dependence in Skyrme effective interactions is investigated to get forces valid beyond the mean field approximation. Preliminary results are presented for infinite symmetric and asymmetric nuclear matter up to pure neutron matter.
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A generalized parameterization of the Skyrme effective force is discussed. Preliminary results are presented for infinite symmetric and asymmetric nuclear matter. In particular, it is shown that an enlarged density dependence based on two terms allows to choose independently the incompressibility and the isoscalar effective mass.
The density dependent term in Skyrme forces is essential, which simulates three-body and many-body correlations beyond the low-momentum two-body interaction. We speculate that a single density term may be insufficient and a higher-order density dependent term is added. The present work investigates the influences of higher-order density dependencies based on extended UNEDF0 and SkM* forces. The global descriptions of nuclear masses and charge radii have been presented. Consequently the extended UNEDF0 force gives a global rms error on binding energies of 1.29 MeV. The influences on fission barriers and equation of state have also been investigated. The perspectives to improve Skyrme forces have also been discussed, including global center-of-mass corrections and Lipkin-Nogami pairing corrections.
Based on the semi-classical extended Thomas-Fermi approach, we study the mass dependence of the symmetry energy coefficients of finite nuclei for 36 different Skyrme forces. The reference densities of both light and heavy nuclei are obtained. Eight models based on nuclear liquid drop concept and the Skyrme force SkM* suggest the symmetry energy coefficient $a_{rm sym}=22.90 pm 0.15 $ MeV at $A=260$, and the corresponding reference density is $rho_Asimeq 0.1$ fm$^{-3}$ at this mass region. The standard Skyrme energy density functionals give negative values for the coefficient of the $I^4$ term in the binding energy formula, whereas the latest Weizsacker-Skyrme formula and the experimental data suggest positive values for the coefficient.
A unified description of finite nuclei and equation of state of neutron stars present a major challenge as well as opportunities for understandings of nuclear interactions.Inspired by the Lee-Huang-Yang formula of hard-sphere gases, we developed effective nuclear interactions with an additional high-order density dependent term.The original Skyrme force SLy4 is widely used in studies of neutron stars but is not satisfied for global descriptions of finite nuclei. The refitted SLy4${}$ force can improve descriptions of finite nuclei but slightly reduces the radius of neutron star of 1.4 solar mass.We found that the extended SLy4 force with a higher-order density dependence can properly describe properties of both finite nuclei and GW170817 binary neutron stars, including the mass-radius relation and the tidal deformability. This demonstrated the essential role of high-order density dependence at ultrahigh densities. Our work provides a unified and predictive model for neutron stars, as well as new insights for the future development of effective interactions.
In the present work we take the non relativistic limit of relativistic models and compare the obtained functionals with the usual Skyrme parametrization. Relativistic models with both constant couplings and with density dependent couplings are considered. While some models present very good results already at the lowest order in the density, models with non-linear terms only reproduce the energy functional if higher order terms are taken into account in the expansion.
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