Wick Equation, the Infinite-Momentum Frame, and Perturbation Theory

The eigenvalues of the Wick equation in the weak-binding limit are found in perturbation theory employing two different approaches: (1) a covariant approach using an integral representation for the Bethe-Salpeter wave function and (2) quantization in the infinite-momentum frame using the technique of Kogut and Soper. The eigenvalues agree to order ${\alpha }^3\ln \alpha$.