Shape coexistence in the microscopically guided interacting boson model
Résumé
Shape coexistence has been a subject of great interest in nuclear physics for
many decades. In the context of the nuclear shell model, intruder excitations
may give rise to remarkably low-lying excited 0+ states associated with different
intrinsic shapes. In heavy open-shell nuclei, the dimension of the shellmodel
configuration space that includes such intruder excitations becomes
exceedingly large, thus requiring a drastic truncation scheme. Such a framework
has been provided by the interacting boson model (IBM). In this article
we address the phenomenon of shape coexistence and its relevant spectroscopy
from the point of view of the IBM. A special focus is placed on the
method developed recently which makes use of the link between the IBM and
the self-consistent mean-field approach based on the nuclear energy density
functional. The method is extended to deal with various intruder configurations
associated with different equilibrium shapes. We assess the predictive
power of the method and suggest possible improvements and extensions, by
considering illustrative examples in the neutron-deficient Pb region, where
shape coexistence has been experimentally studied.