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Matrix Padé Approximants for the and Partial Waves in Nucleon-Nucleon Scattering
Phys. Rev. D 8, 1545 – Published 1 September, 1973
DOI: https://doi.org/10.1103/PhysRevD.8.1545
Abstract
In order to correct the threshold behavior of scalar Padé approximants in scattering, "matrix Padé approximants," which take into account the various positive- and negative-energy states, have been considered by several authors. In a recent paper by Bessis, Turchetti, and Wortman, truncated matrices based on an incomplete set of basis states were used and a qualitative description of the energy dependence of the phase shift was obtained. In this work it is shown that this result is not obtained when a complete set of basis states is used. The main effect of matrix Padé approximants using a complete set of basis states is to introduce an additional attraction at higher energies. Our analysis of the fourth-order graphs is done in a way which allows the external momenta to be completely off shell so that the irreducible graphs can be used as kernels in the Bethe-Salpeter equation. This will make possible the calculation of several higher-order graphs by iterating the Bethe-Salpeter equation.
Comments & Replies
Matrix Padé approximants and the Bethe-Salpeter equation of the interaction
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