Article

Revisiting parton evolution and the large-x limit

LPTHE, Universities of Paris-VI and VII and CNRS, Paris, France; University of Milano-Bicocca and INFN Sezione di Milano-Bicocca, Milan, Italy
Physics Letters B (Impact Factor: 6.02). 12/2005; DOI: 10.1016/j.physletb.2006.02.023
Source: arXiv

ABSTRACT This remark is part of an ongoing project to simplify the structure of the multi-loop anomalous dimensions for parton distributions and fragmentation functions. It answers the call for a “structural explanation” of a “very suggestive” relation found by Moch, Vermaseren and Vogt in the context of the x→1 behaviour of three-loop DIS anomalous dimensions. It also highlights further structure that remains to be fully explained.

0 Bookmarks
 · 
89 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We perform a case study of the behavior of gluon radiation beyond the soft approximation, using as an example the Drell-Yan production cross section at NNLO. We draw a careful distinction between the eikonal expansion, which is in powers of the soft gluon energies, and the expansion in powers of the threshold variable $1 - z$, which involves important hard-collinear effects. Focusing on the contribution to the NNLO Drell-Yan K-factor arising from real-virtual interference, we use the method of regions to classify all relevant contributions up to next-to-leading power in the threshold expansion. With this method, we reproduce the exact two-loop result to the required accuracy, including $z$-independent non-logarithmic contributions, and we precisely identify the origin of the soft-collinear interference which breaks simple soft-gluon factorization at next-to-eikonal level. Our results pave the way for the development of a general factorisation formula for next-to-leading-power threshold logarithms, and clarify the nature of loop corrections to a set of recently proposed next-to-soft theorems.
    10/2014;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Using known all-loop results from the BFKL and generalized double-logarithmic equations and large spin limit we have computed the five-loop anomalous dimension of twist-2 operators without consideration of any wrapping effects. One part of the anomalous dimension was calculated in a usual way with the help of Asymptotic Bethe Ansatz. The rest part, related with the wrapping effects, was reconstructed from known constraints with the help of methods from the numbers theory.
    Journal of High Energy Physics 11/2013; 2014(6). · 6.22 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We confirm recently proposed theorems for the structure of next-to-soft corrections in gauge and gravity theories using diagrammatic techniques, first developed for use in QCD phenomenology. Our aim is to provide a useful alternative insight into the next-to-soft theorems, including tools that may be useful for further study. We also shed light on a recently observed double copy relation between next-to-soft corrections in the gauge and gravity cases.
    Physics Letters B 06/2014; 737. · 6.02 Impact Factor

Full-text (2 Sources)

Download
37 Downloads
Available from
May 31, 2014