A coherent state description of the shape phase transition in even-even Gd isotopes

Three versions of the coherent state model, called CSM, CSM2 and GCSM, are used to describe excitation energies and intraband as well as interband transition probabilities of three interacting bands, ground, beta and gamma, in the even-even isotopes Gd150-160. Common features and differences in the predictions of the three formalisms are commented. All of them yield results which are in fairly good agreement with the available data. New signatures for the transition U(5)-SU(3) are pointed out. It turns out that for some properties this transition is state dependent. Also, there are some properties indicating that in the isotope chain considered there are more than two phases, satisfying the U(5) and SU(3) symmetries, respectively. The formalisms employed here confirm that Gd-154 exhibits features which are specific to the X(5) symmetry.