Infrared safety in factorized hard scattering crosssections
Abstract
The rules of softcollinear effective theory can be used naïvely to write hard scattering crosssections as convolutions of separate hard, jet, and soft functions. One condition required to guarantee the validity of such a factorization is the infrared safety of these functions in perturbation theory. Using e^{+}e^{} angularity distributions as an example, we propose and illustrate an intuitive method to test this infrared safety at one loop. We look for regions of integration in the sum of Feynman diagrams contributing to the jet and soft functions where the integrals become infrared divergent. Our analysis is independent of an explicit infrared regulator, clarifies how to distinguish infrared and ultraviolet singularities in pure dimensional regularization, and demonstrates the necessity of taking zerobins into account to obtain infraredsafe jet functions.
 Publication:

Physics Letters B
 Pub Date:
 June 2009
 DOI:
 10.1016/j.physletb.2009.05.039
 arXiv:
 arXiv:0901.1897
 Bibcode:
 2009PhLB..677..272H
 Keywords:

 Factorization;
 Soft collinear effective theory;
 Jets;
 Event shapes;
 12.38.Bx;
 12.39.St;
 13.66.Bc;
 13.87.a;
 Perturbative calculations;
 Factorization;
 Hadron production in e<sup></sup>e<sup>+</sup> interactions;
 Jets in largeQ<sup>2</sup> scattering;
 High Energy Physics  Phenomenology
 EPrint:
 6 pages, 7 figures, uses elsarticle.cls. v2: extended introduction and clarified discussion of ingredients necessary for proving factorization