Factorization and resummation for collinear poles in QCD amplitudes [electronic resource].

Published:: Washington, D.C. : United States. Dept. of Energy, 2008.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description:: 29 pages : digital, PDF file
Additional Creators:: Stanford Linear Accelerator Center, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

We study the origin of subleading soft and collinear poles of form factors and amplitudes in dimensionally-regulated massless gauge theories. In the case of form factors of fundamental fields, these poles originate from a single function of the coupling, denoted G(α{sub s}), depending on both the spin and gauge quantum numbers of the field. We relate G(α{sub s}) to gauge-theory matrix elements involving the gluon field strength. We then show that G(α{sub s}) is the sum of three terms: a universal eikonal anomalous dimension, a universal non-eikonal contribution, given by the coefficient B{sub δ}(α{sub s}) of δ(1-z) in the collinear evolution kernel, and a process-dependent short-distance coefficient function, which does not contribute to infrared poles. Using general results on the factorization of soft and collinear singularities in fixed-angle massless gauge theory amplitudes, we conclude that all such singularities are captured by the eikonal approximation, supplemented only by the knowledge of B{sub δ}(α{sub s}). We explore the consequences of our results for conformal gauge theories, where in particular we find a simple exact relation between the form factor and the cusp anomalous dimension.

Report Numbers:

E 1.99:slac-pub-13141
slac-pub-13141

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Published through SciTech Connect.
05/28/2008.
"slac-pub-13141"
"arXiv:0805.3515"
Physical Review D FT
Dixon, Lance J.; Sterman, George; Magnea, Lorenzo.

Funding Information:

AC02-76SF00515

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