SURFACE-STATES AND CHIRAL-SYMMETRY ON THE LATTICE

In a Hamiltonian formalism we study chiral symmetry for lattice fermio ns formulated in terms of Shockley surface states bound to a wall in a n extra spatial dimension. For hadronic physics this provides a natura l scheme for taking quark masses to zero without requiring a precise t uning of parameters. We illustrate the chiral anomaly as a flow of sta tes in this extra dimension. We discuss two alternatives for extending the picture to a chiral coupling of gauge fields to such fermions: on e with a small explicit breaking of gauge symmetry and one with heavy mirror fermions.