Variational determination of the stringtension and the glueball mass in (2+1) dimensionalU (1) lattice gauge theory for all values of the coupling constant

Using variational ansätze of the product type we calculate the massgap and the stringtension of (2+1) dimensionalU(1) lattice gauge theory in the Hamiltonian formalism for all values of the coupling constant. In the strong coupling limit our results agree with high order strong coupling series. In the weak coupling limit both, glueball mass and stringtension vanish exponentially with the coupling constant.