THE CRITICAL-BEHAVIOR OF ISING SPINS ON 2D REGGE LATTICES

We performed a high statistics simulation of Ising spins coupled to 2D quantum gravity on toroidal geometries. The tori were triangulated us ing the Regge calculus approach and contained up to 512(2) vertices. W e used a constant area ensemble with an added R2 interaction term, emp loying the dl/l measure. We find clear evidence that the critical expo nents of the Ising phase transition are consistent with the static cri tical exponents and do not depend on the coupling strength of the R2 i nteraction term. We definitively can exclude for this type of model a behaviour as predicted by Boulatov and Kazakov [Phys. Lett. B 186 (198 7) 379] for Ising spins coupled to dynamically triangulated surfaces.