Determination of the ppπ0coupling constant and breaking of charge independence

In a phase-shift analysis of all Pp scattering data below $T_{\mathrm{lab}=350\mathrm{}}$ MeV, where ${\chi }^2$/$N_{\mathrm{DF}=1.07\mathrm{}}$ ($N_{\mathrm{DF}}$ is number of degrees of freedom) is reached, the long- and intermediate-range pp interaction has been studied. Using as intermediate-range interaction the Nijmegen potential, we find for the pp${\pi }^0$ coupling constant ${\mathit{f}}_0^2$=(72.5±0.6)×${10}^{\mathrm{-}3}$ or ${\mathit{g}}_0^2$=13.1±0.1 and for the ${\pi }^0$ mass 134.7±2.1 MeV. Even when we take account of the model dependence due to the potential tail, this value of $f_0^2$ is significantly lower than the value of the charged coupling constant in πN scattering, indicating a large breaking of charge independence.