A recently performed high accuracy measurement indicates the existence of a spin and isospin nonconserving force in neutron-proton scattering. One origin of this effect can be the influence of the up and down quark mass difference on the one gluon exchange spin-orbit force. We include this effect in a resonating group calculation, and find that its contribution is very small compared to that conventional meson-exchange forces.

• Received 7 July 1986

DOI:https://doi.org/10.1103/PhysRevC.34.1779