Three-body Faddeev equations in two-particle Alt-Grassberger-Sandhas form with distorted-wave-Born-approximation amplitudes as effective potentials

Abstract

In this paper, I prove that the sub-Coulomb $A(d,p)B$ reaction amplitude, which is a solution of the three-body Faddeev equations in the Alt-Grassberger-Sandhas (AGS) form, is peripheral if a peripheral is the corresponding DWBA amplitude. Hence the Faddeev's reaction amplitude for the sub-Coulomb $A(d,p)B$ reactions can also be parametrized in terms of the ANC of the $(n\,A)$ bound state. First, I consider the original AGS equations with separable potentials and prove that such equations are peripheral at sub-Coulomb energies. After that, the two-particle AGS equations are derived for the general potentials for sub-Coulomb transfer reactions. The effective AGS potentials are expressed in terms of the DWBA amplitudes for the sub-Coulomb reactions. Again, I demonstrate that the amplitude of the $A(d,p)B$ transfer reaction obtained from the AGS equation is peripheral and can be parametrized in terms of the ANC for the $(nA)$ bound state because the corresponding DWBA amplitude is peripheral. Finally, the AGS equations are generalized by including the optical nuclear potentials in the same manner as it is done in the DWBA. The obtained two-particle AGS equations contain the DWBA effective potentials with distorted waves generated by the sum of the nuclear optical and the channel Coulomb potentials. The AGS equation for the $A(d,p)B$ reactions is analyzed above the Coulomb barrier and it is shown again that the reaction amplitude satisfying generalized AGS equation with optical potentials depends on the ANC if a peripheral is the DWBA amplitude. The two-body AGS equations are generalized by including the intermediate three-body continuum and more than one bound state in each channel.