EXCHANGE OF AN NP PAIR IN ELASTIC PHE-3 BACKWARD SCATTERING AT INTERMEDIATE ENERGIES

Single-loop three-dimensional Feynman diagrams describing the transfer of an np pair in elastic pHe-3 backward scattering with initial proton energies 0.2-1.7 GeV are discussed. It is shown that the sum of these diagrams is equivalent to the first Born approximation in the NN interaction potentials. A mathematical formalism is developed for calculating the amplitude for transfer of an np pair with allowance for the D components of the wave function of the He-3 nucleus. Calculations with the Faddeev five-channel He-3 wave function show that sequential transfer of a noninteracting np pair is dominant in the range of energies 0.6-1.7-GeV and that its contribution is only slightly sensitive to relativistic effects and D components of the He-3 wave function. The exchange of an interacting np pair, including deuteron exchange, makes a negligible contribution.