STRONG-COUPLING SERIES FOR ABELIAN LATTICE GAUGE-MODELS IN 3+1 DIMENSIONS

Linked cluster methods are used to calculate extended strong-coupling series expansions for the ground-state energy, specific heat, scalar, and axial-vector mass gaps in the Z(N) and U(1) Abelian gauge models i n 3+1 dimensions. There is evidence of a singularity at physical coupl ings in the specific heat series, but none in the mass gap series. A c omparison with Monte Carlo data in the U(I) case indicates that there is actually a weak first-order transition.