Convergence Issues in Nucleon-Nucleon Effective Field Theory

The origin of the breakdown scale in an effective field theory treatment of nuclear forces is investigated. Different organizational schemes used in the nonperturbative calculation of nucleon-nucleon scattering seem to break down for different physical reasons. It is argued that the same physics is actually responsible, namely strong two-pion exchange as also observed in the pion scalar form factor. The prospect of extending the applicability of the effective field theory beyond this breakdown point is discussed.