Effective Lagrangian for scale-invariant quantum electrodynamics.

Abstract

In the critical scaling region of quenched, planar QED a composite scalar state plays an essential role in the effective dynamics. We construct an effective potential describing the dynamics of this state for both weak and strong gauge coupling. The scalar propagator at the strong-coupling end point is also constructed using dispersion relation techniques. The role of the four-fermion interaction in the critical region is emphasized and the fate of the scale symmetry elucidated.