Magnetic current and chiral symmetry breaking in quenched QED

We present calculations of the chiral condensate left angle ψψ right angle in quenched compact QED. We demonstrate explicitly that magnetic current in the gauge field configurations is responsible for the breaking of chiral symmetry. The full U(1) configurations from a lattice simulation are factorized into magnetic monopole and photon contributions. The expectation left angle ψψ right angle is computed using the magnetic configurations and compared to results for the full U(1) configurations. It is shown that excellent agreement between the two values of left angle ψψ right angle is obtained if the effect of photons is included. The effect of photons is to ''dress'' the composite operator ψψ; this can be estimated independently by measurements of the physical fermion mass in the photon background. (orig.)