Beyond-mean-field calculations of allowed and first-forbidden β⁻ decays of r-process waiting-point nuclei

¹ GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany
² Fakultät für Physik, Universität Bielefeld, D-33615, Bielefeld, Germany
³ Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008, USA
⁴ National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
⁵ Institut für Kernphysik (Theoriezentrum), Fachbereich Physik, Technische Universität Darmstadt, Schlossgartenstraße 2, 64298 Darmstadt, Germany
⁶ Helmholtz Forschungsakademie Hessen für FAIR, GSI Helmholtzzentrum für Schwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany

^* e-mail: c.robin@gsi.de

Published online: 24 February 2022

Abstract

β-decay rates of neutron-rich nuclei, in particular those located at neutron shell closures, play a central role in simulations of the heavy-element nucleosynthesis and resulting abundance distributions. We present β-decay half-lives of even-even N = 82 and N = 126 r-process waiting-point nuclei calculated in the approach based on relativistic quasiparticle random phase approximation with quasiparticle-vibration coupling. The calculations include both allowed and first-forbidden transitions. In the N = 82 chain, the quasiparticlevibration coupling has an important impact close to stability, as it increases the contribution of Gamow-Teller modes and improves the agreement with the available data. In the N = 126 chain, we find the decay to proceed dominantly via first-forbidden transitions, even when the coupling to vibrations is included.