Hamiltonian strong-coupling expansions for (2+1)-dimensional quantum electrodynamics

Linked cluster expansions are applied to calculate strong-coupling series for lattice quantum electrodynamics in (2+1) dimensions. Series expansions are calculated for the ground-state energy and chiral condensate to O(g-32) in the dimensionless coupling and for the symmetric and antisymmetric photon-ball mass gaps to O(g-16) for various values of the fermion mass. The series do not extend well enough into the weak-coupling regime to allow an accurate matching with the expected weak-coupling behavior, though the correct qualitative behavior is observed for the ground-state energy and chiral condensate.