New Features of the Mandelstam-Leibbrandt Lightcone Gauge

Abstract

This is about new unexpected features of the Mandestam-Leibbrandt prescription found as applied to spacelike Wilson lines. The regularization parameter $\omega$ in the M-L denominator for the spurious poles has to be kept throughout the calculation till the very end or else the integrals do not make sense. We get various `ambiguous' terms of the form ${\omega }^{-\frac{\epsilon }{2}}{\epsilon }^{-2}$ which are not controlled by any sort of Ward identity. These terms cancel out in the sum and the final result is independent of $\omega$. However, for the self energy on the spacelike Wilson line we obtain an unexpected double pole at $\epsilon =0$, using dimensional regularization in $4-\epsilon$ dimensions.

arXiv comment6 pages, tex, two figures not included