Emergent Spectral Degeneracies In The Quantum Phase Transitions In The Interacting Boson Model

The energy degeneracies emerging in the critical region of the interacting boson model are systematically investigated.The results indicate that the level-crossings in the transitions from the U(7)5(8)to the SU(7)3(8)quasidynamical symmetry can induce the approximate spectral degeneracies along the first-order transitional line for large boson number N.The remnant of this type of degeneracies in finite-N systems have been preliminarily identified from the low-lying spectrum of150 Nd.In addition,the similar approximate degeneracies emerging in the phase transition between the U(7)5(8)and SO(7)6(8)quasidynamical symmetries are parallel emphasized.