Covariant spectator theory of np scattering: Effective range expansions and relativistic deuteron wave functions

We present the effective range expansions for the S-1(0) and S-3(1) scattering phase shifts, and the relativistic deuteron wave functions that accompany our recent high precision fits (with chi(2)/N-data similar or equal to 1) to the 2007 world np data below 350 MeV. The wave functions are expanded in a series of analytical functions (with the correct asymptotic behavior at both large and small arguments) that can be Fourier-transformed from momentum to coordinate space and are convenient to use in any application. A FORTRAN subroutine to compute these wave functions can be obtained from the authors.