NN -> NN pi(+) reaction near threshold in a chiral power counting approach- art. no. 034613

Power-counting arguments are used to organize the interactions contributing to the NN-->d pi,pn pi reactions near threshold. We estimate the contribut ions from the three formally leading mechanisms: the Weinberg-Tomozawa (WT) term, the impulse term, and the Delta-excitation mechanism. Subleading but potentially large mechanisms, including S-wave pion rescattering, the Gali lean correction to the WT term, and short-ranged contributions are also exa mined. The WT term is shown to be numerically the largest, and the other co ntributions are found to approximately cancel. Similarly to the reaction pp -->pp pi(0), the computed cross sections are considerably smaller than the data. We discuss possible origins of this discrepancy.