Four-body model of the four-nucleon system

Using a nonrelativistic field theoretic formalism a soluble model of the four-nucleon system is developed and solved numerically. Two- and three-body scattering proceeds through intermediate quasiparticles and the resulting T matrices are separable in momentum space and satisfy two- and three-body unitarity. The 2 + 2 subamplitudes are treated exactly by the convolution method. The resulting four-body equations reduce to single variable integral equations following partial wave decomposition and can be solved numerically by rotation of contour together with matrix inversion. A complete phase shift calculation is performed for the isospin triplet interaction. The differential cross sections for all two-to-two processes initiated by p+³He, n+³H and $d+d$ are compared with experiment for energies up to 25 MeV in the center of mass. Total elastic and reaction cross sections for the processes initiated by n+³H are also calculated and compared with experimental data.