Quasiparticle-vibration coupling in relativistic framework: shell structure of Z=120 isotopes

TL;DR

This paper introduces a fully self-consistent covariant energy density functional theory extension that incorporates quasiparticle-vibration coupling, successfully describing shell structures and evolution in superheavy nuclei like Z=120 isotopes.

Contribution

It presents the first self-consistent relativistic model including quasiparticle-vibration coupling for open-shell nuclei, improving understanding of shell evolution in superheavy elements.

Findings

Proton shell closure at Z=120 is stable.

Neutron shell gap evolves smoothly between N=172 and N=184.

Vibrational corrections significantly affect alpha decay energies.

Abstract

For the first time, the shell structure of open-shell nuclei is described in a fully self-consistent extension of the covariant energy density functional theory. The approach implies quasiparticle-vibration coupling for superfluid systems. One-body Dyson equation formulated in the doubled quasiparticle space of Dirac spinors is solved for nucleonic propagators in tin isotopes which represent the reference case: the obtained energies of the single-quasiparticle levels and their spectroscopic amplitudes are in agreement with data. The model is applied to describe the shell evolution in a chain of superheavy isotopes $^{292,296,300,304}$120 and finds a rather stable proton spherical shell closure at Z = 120. An interplay of the pairing correlations and the quasiparticle-phonon coupling gives rise for a smooth evolution of the neutron shell gap between N = 172 and N = 184 neutron numbers. Vibrational corrections to the alpha decay energies reach several hundred keV and can be either positive and negative, thus also smearing the shell effects.