Solutions of the Faddeev-Yakubovsky equations for the four nucleon scattering states

The Faddeev-Yakubowsky equations in configuration space have been solved for the four nucleon system. The results with an S-wave interaction model in the isospin approximation are presented. They concern the bound and scattering states below the first three-body threshold. The elastic phase shifts for the $N+NNN$ reaction in different $(S,T)$ channels are given and the corresponding low-energy expansions are discussed. Particular attention is paid to the $n+t$ elastic cross section. Its resonant structure is well described in terms of a simple NN interaction. First results concerning the S matrix for the coupled N+NNN-NN+NN channels and the strong deuteron-deuteron scattering length are obtained.