  We perform a nonperturbative calculation of the 1S0 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 no a chiral expansion in
powers of the pion mass. We use dimensional regularization throughout and the
MS-bar subtraction 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 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.
