Sigma model on a squashed sphere with a Wess-Zumino term

A class of two-dimensional sigma models interpolating between CP1 and the SU(2) principal chiral model is discussed. We add the Wess-Zumino-Novikov-Witten term and examine the renormalization group flow of the two coupling constants which characterize the model under consideration. The model flows to the SU(2) Wess-Zumino-Novikov-Witten conformal field theory in the IR limit. There is an ordinary phase in which the model flows from the asymptotically free UV limit of the CP1 model coupled to an extra massless degree of freedom. At higher-loop order we find evidence that there is also a phase in which the model can flow from nontrivial fixed points in the UV. A nonperturbative confirmation of these extra fixed points would be desirable.