Quantum phase transitions and band mixing in 135Ba

Quantum phase transitions and band-mixing phenomena are considered within the framework of a two-state boson–fermion model for the odd-mass 135Ba nucleus. Here, the purpose of the study is to further explore the nature of the interplay between these modalities within the framework of an even–even boson core described by an IBM Hamiltonian coupled to a j = 3/2 fermion as a function of the strength of the coupling constant that links the boson and fermion pictures. The results show that excitation energies and the known E2 strengths of 135Ba are sensitive to the strength of the coupling constant, with a best fit to known experimental results yielding results that lie close to those of the recently proposed E(5/4) model.