Two parameters for three-dimensional wetting transitions

Critical effects at complete and critical wetting in three dimensions are studied using a coupled effective Hamiltonian H[s(y),l(y)]. The model is constructed via a novel variational principle which ensures that the choice of collective coordinate s(y) near the wall is optimal. We highlight the importance of a new wetting parameter Omega(T) which has a strong influence on critical properties and allows the status of long-standing Monte Carlo simulation controversies to be re-examined.