Phase Coexistence in Transitional Nuclei and the Interacting-Boson Model

Abstract

Recent data provide evidence for coexisting phases at low energy in the spherical-deformed transitional nucleus ${}^{152}\mathrm{Sm}$. The nature of the wave functions at the spherical-deformed phase transition in nuclei is analyzed within the framework of the interacting-boson model. It is shown that in the U(5)-SU(3) transition, two phases coexist in a very small region of parameter space around the critical value of the control parameter $\ensuremath{\xi}$. The coexistence region with two minima in the potential shrinks to zero as one moves to the U(5)-O(6) transition. Implications for other systems are briefly mentioned.