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

The European Physical Journal C

Tancredi Carli¹  Pavel Starovoitov²  Frank Siegert³  Gavin P. Salam⁴  Dan Clements⁵  Claire Gwenlan⁶  Amanda Cooper-Sarkar⁶  Mark Sutton⁷ 

[1] Department of Physics, CERN, Geneva, Switzerland;Department of Physics, CERN, Geneva, Switzerland;Nat. Sci. Educ. Center of Part. and HEP, Minsk, Belarus;IPPP, Durham University, Durham, UK;LPTHE, UPMC Univ. Paris 6 and CNRS UMR 7589, Paris 05, France;University of Glasgow, Glasgow, UK;University of Oxford, Oxford, UK;University of Sheffield, Sheffield, UK;

关键词: Large Hadron Collider;    Large Hadron Collider Data;    Parton Density Function;    Posteriori Variation;    Weight Grid;   

DOI  :  10.1140/epjc/s10052-010-1255-0

来源: Springer

【 摘 要 】

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 (Z, W) 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.

【 授权许可】

Unknown