Nucleon-nucleon interaction: Central potential and pion production
  We show that the tail of the chiral two-pion exchange nucleon-nucleon potential is proportional to the $\pi N$ scalar form factor and discuss how it can be translated into effective scalar meson interactions. We then construct a kernel for the process $NN\to\pi NN$, due to the exchange of two pions, which may be used in either three body forces or pion production in NN scattering. Our final expression involves a partial cancellation among three terms, due to chiral symmetry, but the net result is still important. We also find that, at large internucleon distances, the kernel has the same spatial dependence as the central NN potential and we produce expressions relating these processes directly. 
C. M. Maekawa, J. C. Pupin and M. R. Robilotta