Determination of the NNπ coupling constants in NN partial-wave analyses

The NNπ coupling constants are extracted in NN partial-wave analyses. The data base contains all pp and np scattering data below ${\mathit{T}}_{\mathrm{lab}}$=350 MeV. Introducing different coupling constants at the different NNπ vertices, at the pion pole we find for the pp${\mathrm{\pi }}^0$ coupling ${\mathit{f}}_{\mathit{p}}^2$=0.0751(6), for the nn${\mathrm{\pi }}^0$ coupling ${\mathit{f}}_{\mathit{n}}^2$=0.075(2), and for the charged-pion coupling ${\mathit{f}}_{\mathit{c}}^2$=0.0741(5). These results allow only small charge-independence-breaking effects in the NNπ coupling constants. If we assume charge independence, we find ${\mathit{f}}^2$=0.0749(4). The value found for ${\mathit{f}}_{\mathit{c}}^2$ is in agreement with the determination in a recent VPI&SU analysis of the πN scattering data, and with its determination in an analysis of the charge-exchange reaction p¯p→n¯n.