p-Wave pion production from nucleon-nucleon collisions

We investigate p-wave pion production in nucleon-nucleon collisions up to next-to-next-to-leading order in chiral effective field theory. In particular, we show that it is possible to describe simultaneously the p-wave amplitudes in the $pn\to pp{\pi }^{-}$, $pp\to pn{\pi }^{+}$, $pp\to d{\pi }^{+}$ channels by adjusting a single low-energy constant accompanying the short-range operator which is available at this order. This study provides a non-trivial test of the applicability of chiral effective field theory to reactions of the type $NN\to NN\pi$.