The authors give solutions to fundamental problems of the Wess-Zumino-Witten model for general cases. They also find the explicit connection between the crossing matrices of the SU(2) k WZW model and the crossing matrices of the SL(2,q) quantum group; the latter are the quantum Racah coefficients.
The authors have identified critical points in the Wess-Zumino-Witten (WZW) SU(2)5 universality class in the phase diagram of a spin-5/2 chain with frustrated next-nearest-neighbor and 3-site interactions, providing a concrete example of this universality class in a realistic, nonintegrable model. These points lie on a transition line to a dimerized phase and occur when the transition turns from first order into WZW SU(2)3 in agreement with the generic possibilities allowed by field theory arguments.
We suggest the possibility that the two-dimensional SU(2)k Wess-Zumino-Witten (WZW) theory, which has global SO(4) symmetry, can be continued to $2+\ensuremath{\epsilon}$ dimensions by enlarging the symmetry to $\mathrm{SO}(4+\ensuremath{\epsilon})$. This is motivated by the three-dimensional sigma model with SO(5) symmetry and a WZW term, which is relevant to deconfined criticality. If such a continuation exists, the structure of the renormalization group flows at small $\ensuremath{\epsilon}$ may be fixed by assuming analyticity in $\ensuremath{\epsilon}$. This leads to the conjecture that the WZW fixed point annihilates with a new, unstable fixed point at a critical dimensionality dc>2. We suggest that dc<3 for all k, and we compute dc in the limit of large k. The flows support the conjecture that the deconfined phase transition in SU(2) magnets is a ``pseudocritical'' point with approximate SO(5), controlled by a fixed point slightly outside the physical parameter space.