Charge-dependence of the πNN coupling constant and charge-dependence of the NN interaction

The recent determination of the charged πNN coupling constant, gπ± , by the Uppsala Neutron Research Group implies that there may be considerable charge-splitting of the pion coupling constant. We investigate the consequences of this for the charge-independence breaking (CIB) of the 1S0 scattering length, ∆aCIB. We find that ∆aCIB depends sensitively on the difference between gπ± and the neutral πNN coupling constant, gπ0 . Moreover, if g π± is only about 3% larger than g π0 , then the established theoretical explanation of ∆aCIB (in terms of pion mass splitting) is completely wiped out.