Ising Spins on a Gravitating Sphere

We investigated numerically an Ising model coupled to two-dimensional Euclidean gravity with spherical topology, using Regge calculus with the dl=l path-integral measure to discretize the gravita-tional interaction. Previous studies of this system with toroidal topol-ogy have shown that the critical behavior of the Ising model remains in the at-space Onsager universality class, contrary to the predictions of conformal eld theory and matrix models. Implementing the spherical topology as triangulated surfaces of three-dimensional cubes, we nd again strong evidence that the critical exponents of the Ising transition are consistent with the Onsager values, and that KPZ exponents are deenitely excluded.