Eur. Phys. J. A (2016) 52: 176
https://doi.org/10.1140/epja/i2016-16176-0

Regular Article - Theoretical Physics

Proton pygmy resonances: Predictions for N = 20 isotones

Rare Isotope Science Project, Institute for Basic Science, 34047, Daejeon, South Korea

^* e-mail: ppapakon@ibs.re.kr

Received: 10 May 2016
Accepted: 23 May 2016
Published online: 28 June 2016

Abstract

We study theoretically the low-energy electric-dipole response of isotones. We present results from a quasiparticle random-phase approximation (QRPA) and a continuum random-phase approximation (CRPA), and we compare them with results for the mirror nuclei. According to our analysis, enhanced E1 strength is expected energetically well below the giant dipole resonance in the proton-rich isotones. Large amounts of E1 strength in the asymmetric isotones are predicted, markedly unlike their equally asymmetric mirror nuclei, pointing unambiguously to the role of structural effects such as loose binding. A proton-skin oscillation could develop especially in ⁴⁶Fe . The isoscalar response is predicted strong in all isotones. The proper description of non-localized threshold transitions and the nucleon effective mass in mean-field treatments may affect theoretical predictions. We call for systematic theoretical investigations to quantify the role of bulk-matter properties in anticipation of measurements of E1 transitions in proton-rich nuclei.