Global trends of the electric dipole polarizability from shell-model calculations

TL;DR

This paper presents shell-model calculations of electric dipole polarizability for selected nuclei, revealing trends consistent with theoretical models and experimental data, and highlighting the influence of residual interactions.

Contribution

The study advances previous knowledge by providing detailed shell-model calculations of E1 polarizability across p- and sd-shell nuclei, incorporating experimental energies and residual interactions.

Findings

Results are slightly larger than photo-absorption data.

E1 strength increases with mass number, following the TRK sum rule.

Calculations agree with ab initio results at shell closures.

Abstract

Shell-model calculations of the electric dipole (E1) polarizability have been performed for the ground state of selected p- and sd-shell nuclei, substantially advancing previous knowledge. Our results are slightly larger compared with the somewhat more scattered photo-absorption cross-section data, albeit agreeing with ab initio calculations at shell closures and presenting a smooth trend that follows the leptodermus approximation provided by the finite-range droplet model (FRDM). The total E1 strengths also show an increasing trend proportional to the mass number which follows from the classical oscillator strength (TRK) sum rule for the E1 operator. The enhancement of the energy-weighted sum over E1 excitations with respect to the TRK sum rule arises from the use of experimental single-particle energies and the residual particle-hole interaction.