On the MIT bag model: self-adjointness and non-relativistic limit
  This paper is devoted to the mathematical investigation of the MIT bag model, that is the Dirac operator on a smooth and bounded domain with certain boundary conditions. We prove that the operator is self-adjoint and, when the mass goes to infinity, we provide spectral asymptotic results. 
Naiara Arrizabalaga, Lo\"ic Le Treust, Nicolas Raymond
math.SP