Padé-approximant techniques for processing scattering data II. Energy-dependent phase-shift analysis of low-energy4He +2H scattering

Abstract

The general method for Pade-parametrization of experimental scattering data proposed by the authors recently has been applied to analytic parametrizations of theS-matrix and of partialwave amplitudes with the aim of carrying out an energy-dependent phase-shift analysis. It has been shown that the high universality and flexibility of the Pade-approximants make it possible to describe the partial-wave amplitudes by a very small number of parameters (say 2–3 in each partial wave) and to create a universal scheme for parametrization of the full reaction amplitude based on the following hybrid approach: the energy dependence of the inner partial amplitudes is represented by Pade approximants whereas the peripheral part of the full amplitude is taken from the low-order iterations of the exact many-particle Faddeev —Yakubovsky equations. As an example of the technique an energy-dependent phase-shift analysis of low-energy2H +4He scattering has been carried out and the parameters of the 3+ 0,2+ 0 and 1+ 0 resonant states of6Li have been obtained together with the value of the vertex constant of the virtual decay6Lig.s. → →4He +2H. The values of the energy and width obtained from experimental data of the 2+ 0 and particularly of the 1+ 0 level differ significantly from the values published in the literature.