The scaling slope of the anti-symmetric mass gap M of compact U(1)_{2+1}
lattice gauge theory is obtained analytically in the Hamiltonian formalism
using the plaquette expansion. Based on the first four moments of the
Hamiltonian with respect to a one-plaquette mean field state the results
demonstrate clear scaling of M at and beyond the transition from strong to weak
coupling. The scaling parameters determined agree well with the range of
numerical determinations available.Comment: 4 pages, 2 figure