Shape-phase transitions and two-particle transfer intensities

Abstract

In the light of renewed interest in experiments on two-particle transfer reactions, we study the evolution of the transfer spectroscopic intensities as a possible signature of shape-phase transitions. The study is carried out considering chains of even-even nuclei displaying changes in shape, such as from sphericity to axial-symmetric deformed or from sphericity to deformed \ensuremath{\gamma}-unstable nuclei. The evolution of the structure of these nuclei is described in terms of the interacting boson model. In correspondence to the critical points characterizing the phase transitions, the ground-to-ground two-particle transfer matrix elements display a rapid discontinuity, with a corresponding increase in the transition to the excited ${0}^{+}$ states. Simple formulas are given using the intrinsic-frame formalism.