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Parton distributions for the LHC


Type

Article

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Authors

Martin, AD 
Stirling, WJ 
Thorne, RS 
Watt, G 

Abstract

We present the first determination of parton distributions of the nucleon at NLO and NNLO based on a global data set which includes LHC data: NNPDF2.3. Our data set includes, besides the deep inelastic, Drell-Yan, gauge boson production and jet data already used in previous global PDF determinations, all the relevant LHC data for which experimental systematic uncertainties are currently available: ATLAS and LHCb W and Z lepton rapidity distributions from the 2010 run, CMS W electron asymmetry data from the 2011 run, and ATLAS inclusive jet cross-sections from the 2010 run. We introduce an improved implementation of the FastKernel method which allows us to fit to this extended data set, and also to adopt a more effective minimization methodology. We present the NNPDF2.3 PDF sets, and compare them to the NNPDF2.1 sets to assess the impact of the LHC data. We find that all the LHC data are broadly consistent with each other and with all the older data sets included in the fit. We present predictions for various standard candle cross-sections, and compare them to those obtained previously using NNPDF2.1, and specifically discuss the impact of ATLAS electroweak data on the determination of the strangeness fraction of the proton. We also present collider PDF sets, constructed using only data from HERA, Tevatron and LHC, but find that this data set is neither precise nor complete enough for a competitive PDF determination.

Description

Keywords

DEEP-INELASTIC-SCATTERING, DEUTERON STRUCTURE FUNCTIONS, HEAVY FLAVOR PRODUCTION, CURRENT CROSS-SECTIONS, LONGITUDINAL STRUCTURE-FUNCTION, 3-LOOP SPLITTING FUNCTIONS, HIGH STATISTICS MEASUREMENT, INCLUSIVE JET PRODUCTION, H1 VERTEX DETECTOR, TO-LEADING-ORDER

Journal Title

EUR PHYS J C

Conference Name

Journal ISSN

1434-6044
1434-6052

Volume Title

Publisher

Springer Science and Business Media LLC
Sponsorship
Science and Technology Facilities Council (ST/G000581/1)
Science and Technology Facilities Council (ST/J000434/1)