Nuclear energy density optimization

TLDR

The study optimizes a Skyrme‑type nuclear energy density within Hartree–Fock–Bogoliubov theory. The authors simultaneously optimize particle‑hole and particle‑particle channels with a derivative‑free algorithm on a dataset of spherical and deformed nuclei, and assess parameter reliability using statistical methods. The derivative‑free optimization outperforms standard methods in reliability, speed, accuracy, and precision, producing the UNEDFpre parameter set that agrees with experimental masses, radii, and deformations and shows no finite‑size instabilities, and the covariance analysis offers new physics insights.

Abstract

We carry out state-of-the-art optimization of a nuclear energy density of Skyrme type in the framework of the Hartree-Fock-Bogoliubov (HFB) theory. The particle-hole and particle-particle channels are optimized simultaneously, and the experimental data set includes both spherical and deformed nuclei. The new model-based, derivative-free optimization algorithm used in this work has been found to be significantly better than standard optimization methods in terms of reliability, speed, accuracy, and precision. The resulting parameter set UNEDFpre results in good agreement with experimental masses, radii, and deformations and seems to be free of finite-size instabilities. An estimate of the reliability of the obtained parameterization is given, based on standard statistical methods. We discuss new physics insights offered by the advanced covariance analysis.