https://doi.org/10.1140/epjc/s10052-019-7364-5
Letter
A first determination of parton distributions with theoretical uncertainties
1
Department of Physics and Astronomy, VU Amsterdam, De Boelelaan 1081, 1081, HV, Amsterdam, The Netherlands
2
Nikhef, Science Park 105, 1098, XG, Amsterdam, The Netherlands
3
The Higgs Centre for Theoretical Physics, University of Edinburgh, JCMB, KB, Mayfield Rd, Edinburgh, EH9 3JZ, Scotland
4
Tif Lab, Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, 20133, Milan, Italy
5
Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
6
Dipartimento di Fisica G. Occhialini, U2, Università degli Studi di Milano-Bicocca, Piazza della Scienza, 3, 20126, Milan, Italy
7
INFN, Sezione di Milano-Bicocca, 20126, Milan, Italy
8
DAMTP, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA, UK
* e-mail: stefano.forte@mi.infn.it
Received:
27
August
2019
Accepted:
1
October
2019
Published online:
10
October
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.
© The Author(s), 2019
