  It is proven that the rotation of the spin of a polarized neutron is
accompanied by a net nuclear force upon it. This force arises from the weak
nuclear self-interaction of its constituent quarks, whose chiral nature induces
the transfer of a net momentum to the fields of Z and W-bosons. This effect is
linear in Fermi's constant. As a result, it is estimated that along the
spin-flip of a polarized neutron its velocity undergoes a variation of the
order of meters per second.
