Appearance of peak in symmetry energy at N = 126 for Pb isotopic chain within relativistic energy density functional

TL;DR

This paper uses a relativistic energy density functional derived from effective field theory to predict a peak in symmetry energy at neutron number 126 in lead isotopes, aligning with experimental observations.

Contribution

It introduces a new relativistic energy density functional based on E-RMF that accurately predicts symmetry energy peaks in Pb isotopes, improving upon previous functionals.

Findings

Predicts symmetry energy peak at N=126 for Pb isotopes.

Functional accurately reproduces empirical saturation properties.

Peak prediction is consistent across different parameter sets.

Abstract

The newly derived relativistic energy density functional [\textcolor{blue}{ Phys. Rev. C \textbf{103}, 024305 (2021)}], which stems from the effective field theory motivated relativistic mean-field (E-RMF) is employed to establish the appearance of peak/kink in the symmetry energy over the isotopic chain of Pb-nuclei. The coherent density fluctuation model parametrization procedure for finite nuclei is adopted here to obtain the relativistic energy density functional at local density. The relativistic energy density functional from E-RMFT takes precedence over the Br\"uckner energy density functional as it accurately predicts the empirical saturation density and binding energy per nucleon $E/A$, so-called 'Coester Band Problem'. Interestingly, using the relativistic energy density functional, it is possible to predict the peak at $N=126$ for recently developed G3 and widely used NL3 parameter sets, which is not observed for Br\"uckener's functional in-spite of using the E-RMF density. From the present analysis, the newly fitted energy density functional is found to be minutely sensitive to the choice of the parameter sets employed.