We investigate the properties of the Dirac operator on manifolds with
boundaries in presence of the Atiyah-Patodi-Singer boundary condition. An exact
counting of the number of edge states for boundaries with isometry of a sphere
is given. We show that the problem with the above boundary condition can be
mapped to one where the manifold is extended beyond the boundary and the
boundary condition is replaced by a delta function potential of suitable
strength. We also briefly highlight how the problem of the self-adjointness of
the operators in the presence of moving boundaries can be simplified by
suitable transformations which render the boundary fixed and modify the
Hamiltonian and the boundary condition to reflect the effect of moving
boundary.Comment: 24 pages, 3 figures. Title changed, additional material in the
Introduction section, the Application section and in the Discussion section
highlighting some recent work on singular potentials, several references
added. Conclusions remain unchanged. Version matches the version to appear in
PR