title: Critical-point symmetries in boson-fermion systems: the case of shape transitions in odd nuclei in a multiorbit model.
abstract: We investigate phase transitions in boson-fermion systems. We propose an analytically solvable model [E(5/12)] to describe odd nuclei at the critical point in the transition from the spherical to gamma-unstable behavior. In the model, a boson core described within the Bohr Hamiltonian interacts with an unpaired particle assumed to be moving in the three single-particle orbitals j=1/2, 3/2, 5/2. Energy spectra and electromagnetic transitions at the critical point compare well with the results obtained within the interacting boson-fermion model, with a boson-fermion Hamiltonian that describes the same physical situation.
authors.affiliation: Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, Apartado 1065, 41080 Sevilla, Spain.
authors.forename: C E
authors.initials: CE
authors.lastname: Alonso
authors.forename: J M
authors.initials: JM
authors.lastname: Arias
authors.forename: A
authors.initials: A
authors.lastname: Vitturi