A First Determination of Parton Distributions with Theoretical Uncertainties
Abstract
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.
Keywords
Cite
@article{arxiv.1905.04311,
title = {A First Determination of Parton Distributions with Theoretical Uncertainties},
author = {The NNPDF Collaboration and Rabah Abdul Khalek and Richard D. Ball and Stefano Carrazza and Stefano Forte and Tommaso Giani and Zahari Kassabov and Emanuele R. Nocera and Rosalyn L. Pearson and Juan Rojo and Luca Rottoli and Maria Ubiali and Cameron Voisey and Michael Wilson},
journal= {arXiv preprint arXiv:1905.04311},
year = {2019}
}
Comments
8 pages, 6 figures, PDF sets available from https://data.nnpdf.science/nnpdf31_th/. Final Version, to be published in EPJC letters. Appendix removed, several small improvements including brief discussion of usage