The European Physical Journal C

, Volume 66, Issue 3–4, pp 503–524

A posteriori inclusion of parton density functions in NLO QCD final-state calculations at hadron colliders: the APPLGRID project

  • Tancredi Carli
  • Dan Clements
  • Amanda Cooper-Sarkar
  • Claire Gwenlan
  • Gavin P. Salam
  • Frank Siegert
  • Pavel Starovoitov
  • Mark Sutton
Open Access
Special Article - Tools for Experiment and Theory
  • 486 Downloads

Abstract

A method to facilitate the consistent inclusion of cross-section measurements based on complex final-states from HERA, TEVATRON and the LHC in proton parton density function (PDF) fits has been developed. This can be used to increase the sensitivity of LHC data to deviations from Standard Model predictions. The method stores perturbative coefficients of NLO QCD calculations of final-state observables measured in hadron colliders in look-up tables. This allows the a posteriori inclusion of parton density functions (PDFs), and of the strong coupling, as well as the a posteriori variation of the renormalisation and factorisation scales in cross-section calculations. The main novelties in comparison to original work on the subject are the use of higher-order interpolation of Lagrangian form, which substantially improves the trade-off between accuracy and memory use, and a CPU and computer memory optimised way to construct and store the look-up table using modern software tools. It is demonstrated that a sufficient accuracy on the cross-section calculation can be achieved with reasonably small look-up table size by using the examples of jet production and electro-weak boson (ZW) production in proton-proton collisions at a center-of-mass energy of 14 TeV at the LHC. The use of this technique in PDF fitting is demonstrated in a PDF-fit to HERA data and simulated LHC jet cross-sections as well as in a study of the jet cross-section uncertainties at various centre-of-mass energies.

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Copyright information

© Springer-Verlag / Società Italiana di Fisica 2010

Authors and Affiliations

  • Tancredi Carli
    • 1
  • Dan Clements
    • 2
  • Amanda Cooper-Sarkar
    • 3
  • Claire Gwenlan
    • 3
  • Gavin P. Salam
    • 4
  • Frank Siegert
    • 5
  • Pavel Starovoitov
    • 1
    • 6
  • Mark Sutton
    • 7
  1. 1.Department of PhysicsCERNGenevaSwitzerland
  2. 2.University of GlasgowGlasgowUK
  3. 3.University of OxfordOxfordUK
  4. 4.LPTHEUPMC Univ. Paris 6 and CNRS UMR 7589Paris 05France
  5. 5.IPPPDurham UniversityDurhamUK
  6. 6.Nat. Sci. Educ. Center of Part. and HEPMinskBelarus
  7. 7.University of SheffieldSheffieldUK

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