Universality of Nonperturbative Effects in Event Shapes

Abstract

Nonperturbative effects in event shape distributions can be characterized by shape functions derived in the eikonal approximation or, equivalently, from soft-collinear effective theory. The use of energy flow operators and the boost invariance of the Wilson lines of soft gluons in the shape functions leads to a proof of universality for power corrections to the mean values of event shapes, without invoking the single gluon approximation.

Comments: 4 pages; to appear in the Proceedings of the FRIF Workshop on First Principles Non-Perturbative QCD of Hadron Jets (Paris, 12-14 January 2006); ReVTeX4, uses slac_one.rtx (included)