A unified S-matrix framework of quantum singular interactions is presented
for the comparison of self-adjoint extensions and physical renormalization. For
the long-range conformal interaction the two methods are not equivalent, with
renormalization acting as selector of a preferred extension and regulator of
the unbounded Hamiltonian.Comment: 19 pages, including 2 figures. The title and abstract were changed to
more accurately reflect the content. The text was rearranged into sections,
with several equations and multiple paragraphs added for clarity; and a few
typos were corrected. The central equations and concepts remain unchanged