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A First Determination of Parton Distributions with Theoretical Uncertainties

Research output: Contribution to journalLetter

  • The NNPDF Collaboration
  • Rabah Abdul Khalek
  • Richard D. Ball
  • Stefano Carrazza
  • Stefano Forte
  • Tommaso Giani
  • Zahari Kassabov
  • Emanuele R. Nocera
  • Rosalyn L. Pearson
  • Juan Rojo
  • Luca Rottoli
  • Maria Ubiali
  • Cameron Voisey
  • Michael Wilson

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Original languageEnglish
Number of pages8
JournalEuropean Physical Journal C: Particles and Fields
Issue number838
Publication statusPublished - 10 Oct 2019


The parton distribution functions (PDFs) which characterize the structure of the proton are currently one of the dominant sources of uncertainty in the predictions for most processes measured at the Large Hadron Collider (LHC). Here we present the first extraction of the proton PDFs that accounts for the missing higher order uncertainty (MHOU) in the fixed-order QCD calculations used in PDF determinations. We demonstrate that the MHOU can be included as a contribution to the covariance matrix used for the PDF fit, and then introduce prescriptions for the computation of this covariance matrix using scale variations. We validate our results at next-to-leading order (NLO) by comparison to the known next order (NNLO) corrections. We then construct variants of the NNPDF3.1 NLO PDF set that include the effect of the MHOU, and assess their impact on the central values and uncertainties of the resulting PDFs.

    Research areas

  • hep-ph, hep-ex, nucl-th

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