The zero mode of an extra-dimensional component of gauge potentials serves as
a 4D Higgs field in the gauge-Higgs unification. We examine QED on M4×S1 and determine the mass and potential of a 4D Higgs field (the A5
component) at the two loop level with gauge invariant reguralization. It is
seen that the mass is free from divergences and independent of the
renormalization scheme.Comment: 18 pages, 1 figur