Light-cone gauge and the (causal) principal-value prescription

The principal-value (PV) prescription constrained with causality is used to treat the unphysical pole (kn)-1 in the basic one-loop light-cone integral. It is shown that the so-modified prescription avoids the emergence of double-pole singularities, contrary to what has been previously obtained in the PV scheme without causality. However, there remains an overall factor which does not agree with the results derived in the Mandelstam-Leibbrandt (ML) prescription. This overall factor is a remnant coming from the definition of the prescription proper. © 1990 The American Physical Society.