Superstrings with boundary fermions

The Green-Schwarz action for an open superstring with additional boundaryfermions, representing Chan-Paton factors, is studied at the classical level.The boundary geometry is described by a bundle, with fermionic fibres, over thesuper worldvolume of a D-brane together with a map from the total space intothe type II target superspace. This geometry is constrained by the requirementof kappa-symmetry on the boundary together with the use of the equations ofmotion for the fermions. There are two constraints which are formally similarto those that arise in the abelian case but which differ because of thedependence on the additional coordinates. The model, when quantised, would be acandidate for a fully kappa-symmetric theory of a stack of coincident D-branesincluding a non-abelian Born-Infeld sector. The example of the D9-brane in aflat background is studied. The constraints on the non-abelian field strengthare shown to be in agreement with those derived from the pure spinor approachto the superstring. A covariant formalism is developed and the problem ofquantisation is discussed.Comment: 26 pages. Typographical errors corrected. References adde