  Techniques developed for handing inverse-power-law potentials in atomic
physics are applied to the tensor one-pion exchange potential to determine the
regions in which it can be treated perturbatively. In S-, P- and D-waves the
critical values of the relative momentum are less than or of the order of 400
MeV. The RG is then used to determine the power counting for short-range
interaction in the presence of this potential. In the P-and D-waves, where
there are no low-energy bound or virtual states, these interactions have
half-integer RG eigenvalues and are substantially promoted relative to naive
expectations. These results are independent of whether the tensor force is
attractive or repulsive. In the 3S1 channel the leading term is relevant, but
it is demoted by half an order compared to the counting for the effective-range
expansion with only a short-range potential. The tensor force can be treated
perturbatively in those F-waves and above that do not couple to P- or D-waves.
The corresponding power counting is the usual one given by naive dimensional
analysis.
