Infrared Divergences from Soft and Collinear Gauge Bosons

Abstract

I review the Lee-Nauenberg thereom and discuss its inclusion of photons which are disconnected at the level of the S-matrix but connected at the level of the cross-section when there are initial and final state charged particles. I then expose a new set of soft collinear divergences in massless gauge theories which are omitted in the standard Lee-Nauenberg approach. It seems that highly questionable assumptions are needed to obtain finite cross-sections.

Comments: 6 pages, 6 .jpg figures. Talk given at the Ninth Workshop on Non-Perturbative QCD, Paris, June 2007