Dirac-like operators on the Hilbert space of differential forms on   manifolds with boundaries
  The problem of self-adjoint extensions of Dirac-type operators in manifolds with boundaries is analysed. The boundaries might be regular or non-regular. The latter situation includes point-like interactions, also called delta-like potentials, in manifolds of dimension higher than one. Self-adjoint boundary conditions for the case of dimension 2 are obtained explicitly. 
J.M. P\'erez-Pardo
math-ph math.MP