Dynamically selected vacuum field configuration in massless QED

Abstract

Using the Euclidean functional-integral formalism an effective bilocal action is derived for massless quantum electrodynamics (QED). The vacuum field equation is obtained from this action and it is shown that the dynamically selected vacuum field configuration in massless QED is a class of degenerate, nontrivial field configurations related to each other through a one-parameter Abelian chiral transformation. The existence of a chirally degenerate vacuum establishes that the chiral symmetry manifest in the action of massless QED becomes a hidden symmetry when a particular choice of the vacuum configuration is made. Thus it is established that chiral symmetry is spontaneously broken in the vacuum of massless QED.