  We consider nucleon-nucleon (NN) interactions from chiral effective field
theory. In this work we restrict ourselves to the elastic NN scattering. We
apply the N/D method to calculate the NN partial waves taking as input the
one-pion exchange discontinuity along the left-hand cut. This discontinuity is
amenable to a chiral power counting as discussed by Lacour, Oller and Meissner
[Ann. Phys. (NY) 326, 241 (2011)], with one-pion exchange as its leading order
contribution. The resulting linear integral equation for a partial wave with
orbital angular momentum L>=2 is solved in the presence of L-1 constraints, so
as to guarantee the right behavior of the D and higher partial waves near
threshold. The calculated NN partial waves are based on dispersion relations
and are independent of regulator. This method can also be applied to higher
orders in the calculation of the discontinuity along the left-hand cut and
extended to triplet coupled partial waves.
