Shape phase mixing in critical point nuclei

TL;DR

This paper introduces a hybrid nuclear model that interpolates between known critical point symmetries, effectively describing shape phase mixing and spectral properties of nuclei near quantum phase transitions.

Contribution

The model combines gamma-stable and gamma-rigid conditions through a rigidity parameter, unifying X(5), X(3), and X(4) symmetries and improving spectral predictions.

Findings

Reveals significant shape phase mixing in critical nuclei.

Shows evolution of shape mixing with neutron and proton numbers.

Provides better energy spectra and transition descriptions.

Abstract

Spectral properties of nuclei near the critical point of the quantum phase transition between spherical and axially symmetric shapes are studied in a hybrid collective model which combines the $\gamma$-stable and $\gamma$-rigid collective conditions through a rigidity parameter. The model in the lower and upper limits of the rigidity parameter recovers the X(5) and X(3) solutions respectively, while in the equally mixed case it corresponds to the X(4) critical point symmetry. Numerical applications of the model on nuclei from regions known for critical behavior reveal a sizable shape phase mixing and its evolution with neutron or proton numbers. The model also enables a better description of energy spectra and electromagnetic transitions for these nuclei.