NON-MEAN-FIELD EXPONENTS IN STRONGLY COUPLED QUENCHED QED

We study quenched quantum electrodynamics (QED) on a lattice in the noncompact formulation. Near the chiral critical point, we avoid critical slowing down using fast-Fourier-transform methods which allow us to obtain critical indices with good accuracy. Using lattices of 16(4) and 24(4) sites and masses between 0.025 and 0.0007 (lattice units) we found that the critical behavior of QED is described by power laws with critical exponents differing from mean-field results. The critical coupling is beta-c = 0.257 +/- 0.001, the exponent delta is 2.2 +/- 0.1, and the magnetic exponent beta(m) is 0.78 +/- 0.08. A physical explanation of our results is presented.