Nuclear pygmy modes and the dynamics of the nuclear skin

TL;DR

This paper investigates pygmy resonances in nuclei, revealing their connection to nuclear skin properties and their impact on nuclear response functions relevant for astrophysical processes.

Contribution

It introduces a theoretical approach combining density functional theory and multi-phonon methods to study low-energy nuclear excitations and their relation to neutron and proton skins.

Findings

Identification of new pygmy dipole and quadrupole resonances

Nuclear skins influence magnetic response of nuclei

Response functions affect photonuclear reaction cross sections

Abstract

The information on pygmy resonances reveals new aspects on the isospin dynamics of the nucleus with important astrophysical consequences. In this connection, the precise knowledge of nuclear response functions plays a key role in the determination of photonuclear reactions cross sections which are of importance for the synthesis of heavy neutron-rich elements. For that purpose, a theoretical method based on density functional theory and multi-phonon approach is applied for investigations of nuclear excitations with different multipolarities and energies in stable and exotic nuclei. The possible relation of low-energy modes to the properties of neutron or proton skins is systematically investigated for isotonic and isotopic chains. Our studies of dipole and quadrupole response functions and the corresponding transition densities indicate new pygmy dipole and pygmy quadrupole resonances, describing oscillations of the nuclear skin. Also, the presence of skins is found to affect the magnetic response of nuclei.