Nonperturbative evaluation of the few-body states for scalar χ2φ interaction Original Resear

A knowledge of nonpertubative propagators is often needed when the standard perturbative methods are not applicable. An example of this is the bound state problem in field theory. While a nonperturbative result is valuable by itself, it is also an important guide for those who work on developing phenomenological models for the nonperturbative problem. The Feynman–Schwinger representation approach provides a convenient framework for calculating nonperturbative propagators. In this paper we provide an algorithm for computing 1-, 2-, and 3-body bound states with the inclusion of all self energies, vertex corrections, ladder and crossed ladder exchanges. The calculation is done in the quenched approximation by ignoring the matter loops. We provide simulation results for 1-, 2- and 3-body states.