Nucleon-nucleon scattering from effective field theory

We perform a non-perturbative calculation of the S-1(0) NN scattering amplitude, using an effective field theory (EFT) expansion, The expansion we advocate is a modification of what has been used previously; it is not a chiral expansion in powers of m(pi). We use dimensional regularization throughout, and the <(MS)over bar> renormalization scheme; our final result depends only on physical observables. We show that the EFT expansion of the quantity \p\ cot delta(p) converges at momenta much greater than the scale Lambda that characterizes the derivative expansion of the EFT Lagrangian. Our conclusions are optimistic about the applicability of an EFT approach to the quantitative study of nuclear matter.