Constraints, limits and extensions for nuclear energy functionals

TL;DR

This paper examines the behavior of Skyrme forces in nuclear physics, highlighting correlations between resonance results and the equation of state, and proposes using these as constraints in force fitting.

Contribution

It introduces a method to constrain Skyrme force parameters using RPA results and EOS characteristics, improving nuclear force models.

Findings

Identified correlations between resonance energies and EOS parameters.

Selected a subset of Skyrme forces based on these correlations.

Proposed a new approach for fitting nuclear energy density functionals.

Abstract

In the present contribution, we discuss the behavior of Skyrme forces when they are employed to study both neutron stars and giant resonance states in 208Pb within the fully self-consistent Random Phase Approximation (RPA). We point out that clear correlations exist between the results for the isoscalar monopole and isovector dipole resonances (ISGMR and IVGDR), and definite quantities which characterize the equation of state (EOS) of uniform matter. We propose that the RPA results or, to some extent, the mentioned EOS parameters, are used as constraints when a force is fitted. This suggestion can be valid also when the fit of a more general energy density functional is envisaged. We use our considerations to select a limited number of Skyrme forces (10) out of a large sample of 78 interactions.