Comparison of instant form and front form one-particle exchange models.

Abstract

We study the use of the Okubo method for constructing effective two-particle, instant form and front form, one-particle exchange models, starting from quantum field theory vertices. The truncation of the field theory that is made in applying the Okubo method leads to mass operators that are not exactly Poincar{acute e} invariant. It is found that when the spurious terms that destroy the exact Poincar{acute e} invariance are eliminated the instant and front form potentials come out essentially the same, however they wind up in slightly different two-particle Lippmann-Schwinger equations. In order to study the practical consequences of this difference, a numerical comparison is made between instant and front form one-meson-exchange models of the two-nucleon system that have been fit to the same partial-wave analysis of the two-nucleon data. These models assume the exchange of {pi}, {eta}, {rho}, {omega}, {delta}, and {sigma} mesons. No dramatic differences are found between the instant form and front form vertex parameters obtained from the fits. {copyright} {ital 1996 The American Physical Society.}