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 ${\beta }_c=0.257\mathrm{}\pm 0.001$, 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.