The energy dependence of the mixing parameter epsilon for 3S1-3D1 neutron-proton scattering

In this article, we show that the pole in the expansion of tan(2 epsilon )/(2k2) is a consequence of the fact that for the two-nucleon system the second coefficient in the expansion of the M matrix element M22 has the same sign as the first but its magnitude is much larger. It is not necessary to assume that the pion cut is important for this particular function.