The method of regions and next-to-soft corrections in Drell–Yan production

Oct 23, 2014
8 pages
Published in:
  • Phys.Lett.B 742 (2015) 375-382
  • Published: Mar 6, 2015
e-Print:
Report number:
  • EDINBURGH-2014-18,
  • NIKHEF-2014-039,
  • ITF-UU-14-24

Citations per year

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Abstract: (Elsevier)
We perform a case study of the behaviour 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 factorisation 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.
Note:
  • 18 pages, 1 figure
  • Drell-Yan process
  • gluon: fusion
  • gluon: radiation
  • gluon: energy
  • gluon: collinear
  • approximation: eikonal
  • approximation: higher-order
  • threshold: correction
  • threshold: expansion
  • expansion: higher-order