Glauber Gluon Effects in Soft Collinear Factorization

TL;DR

This paper investigates the role of Glauber gluons in soft-collinear effective theory, demonstrating their cancellations in inclusive processes and clarifying their impact on factorization in QCD.

Contribution

It explicitly incorporates Glauber modes into SCET, proving their cancellations and elucidating their effects on soft-collinear factorization.

Findings

Glauber gluon exchanges cancel in inclusive processes.

Active-spectator Glauber interactions are harmless for summation.

Graphical analysis links perturbative QCD cancellations to operator methods.

Abstract

Effects of Glauber gluons, which cause the elastic scattering process between different jets, are studied in the frame of soft-collinear effective theory(SCET). Glauber modes are added into the Lagrangian before integrated out, which is helpful in studies on Glauber couplings of collinear and soft particles explicitly. It is proved that interactions after the hard collision cancel out in processes inclusive enough. So are interactions with the light cone coordinates Sx^{+}$ and $x^{-}$ greater than those of the hard collision. Eikonalization of Glauber couplings of active particles and absorption of active-active and active-soft and active-spectator Glauber exchanges into soft and collinear Wilson lines are discussed, which is related to loop level definitions of Glauber gluons here. The active-spectator coherence are proved to be harmless on inclusive summation of spectator-spectator and spectator-soft Glauber exchanges. Based on this result, spectator-spectator and spectator-soft Glauber exchanges are proved to cancel out in processes considered here. Graphic aspects of the cancellation are also discussed to explain relations between the graphic cancellation of Glauber gluons in the frame of perturbative QCD and operator level skills in the paper.