Chiral potentials, perturbation theory, and the $^{1}$S$_{0}$ channel of NN scattering

Nucleon-nucleon phase shifts obtained from experimental data and the chiral expansion for the long-distance part of the NN interaction are used to obtain information about the short-distance piece of the NN potential that is at work in the $^{1}$S$_{0}$ channel. The energy dependence produced by short-distance dynamics is well approximated by a two-term polynomial for T$_{ lab}\le $ 200 MeV if the scale of separation between ``long-'' and ``short-'' distance physics is chosen to be less than 1.8 fm. A quantitative description of NN dynamics is possible, at least in this channel, by treating the long-distance parts of the chiral NN potential in perturbation theory.