Approximation of one-dimensional relativistic point interactions by regular potentials revised

We show that the one-dimensional Dirac operator with quite general point interaction may be approximated in the norm resolvent sense by the Dirac operator with a scaled regular potential of the form 1/ε h(x/ε )⊗ B , where B is a suitable 2× 2 matrix. Moreover, we prove that the limit does not depend on the particular choice of h as long as it integrates to a constant value.