Partial dynamical symmetry and odd-even staggering in deformed nuclei

Partial dynamical symmetry (PDS) is shown to be relevant for describing the odd-even staggering in the $\gamma$-band of $^{156}$Gd while retaining solvability and good SU(3) symmetry for the ground and $\beta$ bands. Several classes of interacting boson model Hamiltonians with SU(3) PDS are surveyed.