Determination of the chiral coupling constants c3 and c4 in new pp and np partial-wave analyses

Phys.Rev. C67 (2003) 044001 As a first result of two new partial-wave analyses, one of the pp and another one of the np scattering data below 500 MeV, we report a study of the long-range chiral two-pion exchange interaction which contains the chiral coupling constants c1, c3, and c4. By using as input a theoretical value for c1 we are able to determine in pp as well as in np scattering accurate values for c3 and c4. The values determined from the pp data and independently from the np data are in very good agreement, indicating the correctness of the chiral two-pion exchange interaction. The weighted averages are c3 = -4.78(10) / GeV and c4 = 3.96(22) / GeV, where the errors are statistical. The value of c3 is best determined from the pp data and that of c4 from the np data.