Radiation pions in two-nucleon effective field theory

Abstract

For interactions involving two or more nucleons it is useful to divide pions into three classes: potential, radiation, and soft. The momentum threshold for the production of radiation pions is $Q_r=\sqrt{M_N{m}_{\pi }}$. We show that radiation pions can be included systematically with a power counting in $Q_r$. The leading order radiation pion graphs which contribute to NN scattering are evaluated in the PDS and OS renormalization schemes and are found to give a small contribution. The power counting for soft pion contributions is also discussed.

Comments: 21 pages, 3 figs, journal version