Gauge-invariant signal for gauge-symmetry breaking

The effective potential is computed to order ℏ in an Abelian gauge theory---scalar electrodynamics. The calculation is performed first in the ghost-requiring $R_{\xi }$ gauges. The corresponding expression is also derived from the unitary Lagrangian. We discuss the gauge dependence of the effective potential and its minima in connection with spontaneous symmetry breakdown; and we interpret the unitary computation to be the physically relevant one.