Generalized action principle and superfield equations of motion for D=10 Dp-branes

The action for the D = 10 type II Dirichlet super p-branes, which has been obtained recently, is reconstructed in a more geometrical form involving Lorentz harmonic variables, This new (Lorentz harmonic) formulation possesses kappa-symmetry in an irreducible form and is used as a basis for applying a generalized action principle that provides the superfield equations of motion and clarifies the geometrical nature of the kappa-symmetry of these models, The case of a Dirichlet super 3-brane is considered in detail. (C) 1997 Elsevier Science B.V.