Jm. Roman et R. Tarrach, THE REGULATED 4-PARAMETER ONE-DIMENSIONAL POINT INTERACTION, Journal of physics. A, mathematical and general, 29(18), 1996, pp. 6073-6085
The general four-parameter point interaction in one-dimensional quantu
m mechanics is regulated. It allows the exact solution, but not the pe
rturbative one. We conjecture that this is due to the interaction not
being asymptotically free. We then propose a different breakup of unpe
rturbed theory and interaction, which now is asymptotically free but l
eads to the same physics. The corresponding regulated potential can be
solved both exactly and perturbatively, in agreement with the conject
ure.