Impact of collective vibrations on quasiparticle states of open-shell odd-mass nuclei and possible interference with the tensor force

TL;DR

This paper demonstrates that quasiparticle-vibration coupling significantly improves the theoretical description of energy splittings in open-shell odd-mass nuclei, reducing the need for a strong tensor force and highlighting the interplay of both effects.

Contribution

It shows for the first time that quasiparticle-vibration coupling can account for energy splittings traditionally attributed solely to tensor interactions.

Findings

QVC improves energy splitting predictions

Weaker tensor interaction suffices when including QVC

Both tensor force and QVC are necessary for accurate modeling

Abstract

The energy splittings between the proton $1h_{11/2}$ and $1g_{7/2}$ states in the Sb (Z=51) isotopes and the neutron $1i_{13/2}$ and $1h_{9/2}$ states in the ${N=83}$ isotones are analyzed within relativistic quasiparticle-vibration coupling (QVC) model. Although a common viewpoint is that an effective tensor interaction is needed to reproduce these splittings, we show, for the first time, that quasiparticle-vibration coupling also improves their description considerably. The remaining differences between the experiment and the QVC calculations point to a complex scenario in which both tensor interaction and quasiparticle-vibration coupling are needed to reproduce accurately the observed energy splittings. This scenario, however, requires a considerably weaker tensor interaction as compared with the previous estimates.