Chiral three-nucleon forces from p-wave pion production

Production of p-wave pions in nucleon-nucleon collisions is studied according to an improved power counting that embodies the constraints of chiral symmetry. Contributions from the first two nonvanishing orders are calculated. We find reasonable convergence and agreement with data for a spin-triplet cross section in pp-->pppi(0), with no free parameters. Agreement with existing data for a spin-singlet cross section in pp-->pnpi(+) constrains a short-range operator shown recently to contribute significantly to the three-nucleon potential.