2-BODY T-MATRICES WITHOUT ANGULAR-MOMENTUM DECOMPOSITION - ENERGY ANDMOMENTUM DEPENDENCES

The two-body T-matrix is calculated directly as function of two vector momenta for different Malfliet-Tjon-type potentials. At a few hundred MeV projectile energy the total amplitude is quite a smooth function showing only a strong peak in forward direction. In contrast, the corr esponding partial-wave contributions, whose number increases with incr easing energy, become more and more oscillatory with increasing energy . The angular and momentum dependence of the full amplitude is studied and displayed on as well as off the energy shell as function of posit ive and negative energies. The behaviour of the T-matrix in the vicini ty of bound-state poles and resonance poles in the second energy sheet is studied. It is found that the angular dependence of T exhibits ver y characteristic properties in the vicinity of those poles, which are given by the Legendre function corresponding to the quantum number eit her of the bound stale or the resonance (or virtual) state. This behav iour is illustrated along numerical examples.