NONPERTURBATIVE STUDY OF GENERALIZED LADDER GRAPHS IN A THETA(2)CHI THEORY

The Feynman-Schwinger representation is used to construct scalar-scala r bound states for the set of all ladder and crossed-ladder graphs in a phi(2) chi theory in 3 + 1 dimensions. The results are compared to t hose of the usual Bethe-Salpeter equation in the ladder approximation and of several quasipotential equations. Particularly for large coupli ngs, the ladder predictions are seen to underestimate the binding ener gy significantly as compared to the generalized ladder case, whereas t he solutions of the quasipotential equations provide a better correspo ndence. Results for the calculated bound state wave functions are also presented.