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.