Semi-decoupled bands in the even Hg isotopes

The odd-parity yrast states of the isotopes ^190–200Hg are studied in a model of two quasiparticles coupled to an oblate rotor and interacting by a surface delta interaction. The experimental energy spectra and the enhancement of E2 transition probabilities are well explained by the model. The pure Coriolis coupling problem (i.e., the problem obtained when the residual interaction is suppressed) is investigated in detail. It is shown that the main effect of the Coriolis force is to decouple the high-spin quasiparticle originating in the neutron $\text{1}\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ subshell from the system of the rotor and the low-spin quasiparticle. We study the coupling of a particle to an axially symmetric rotor, which has an intrinsic spin along its symmetry axis, and derive a good approximate solution to the problem.