ZERO MODES AND DISPLACEMENT SYMMETRY IN ELECTRODYNAMICS

The global residual gauge symmetry of electrodynamics, the displacemen t symmetry, is discussed within the Weyl-gauge formulation and used to characterize different phases of the Maxwell field coupled to matter. Unlike other global symmetries, the displacement symmetry, in the abs ence of interactions or in the weak coupling regime, is realized in th e Nambu-Goldstone mode. The displacement symmetry will be shown to be realized in the Wigner-Weyl mode in the plasma and superconducting sta tes; this discussion develops a novel perspective of the plasma oscill ations. Other examples are the states of the Schwinger model and the n on-perturbative phase of the Abelian Higgs model. The Higgs mechanism is interpreted as formation of a phase with a high degree of symmetry. Finite photon mass and shielding of external fields will be recognize d as the characteristic properties of these symmetric phases. (C) 1994 Academic Press, Inc.