A number of arguments purport to show that quantum field theory cannot be given an interpretation in terms localizable particles. We show, light such arguments, the classical $\hbar\to 0$ limit can aid our understanding particle content theories. In particular, we demonstrate for massive Klein-Gordon field, limits operators understood encode local information about particles corresponding theory.

A bstract precise link is derived between scalar-graviton S-matrix elements and expectation values of operators in a worldline quantum field theory (WQFT), both used to describe classical scattering black holes. The formally provided by path integral representation the graviton-dressed scalar propagator, which may be inserted into traditional definition terms time-ordered correlators. To calcul...