Reweighting and unweighting of parton distributions and the LHC W lepton asymmetry data

NNPDF Collaboration, Richard D. Ball, Valerio Begone, Francesco Cerutti, Luigi Del Debbio, Stefano Forte, Alberto Guffanti, Nathan P. Hartland, Jose I. Latorre, Juan Rojo, Maria Ubiali

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We develop in more detail our reweighting method for incorporating new datasets in parton fits based on a Monte Carlo representation of PDFs. After revisiting the derivation of the reweighting formula, we show how to construct an unweighted PDF replica set which is statistically equivalent to a given reweighted set. We then use reweighting followed by unweighting to test the consistency of the method, specifically by verifying that results do not depend on the order in which new data are included in the fit via reweighting. We apply the reweighting method to study the impact of LHC W lepton asymmetry data on the NNPDF2.1 set. We show how these data reduce the PDF uncertainties of light quarks in the medium and small x region, providing the first solid constraints on PDFs from LHC data. (C) 2011 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)608-638
Number of pages31
JournalNuclear physics b
Issue number3
Publication statusPublished - 21 Feb 2012

Keywords / Materials (for Non-textual outputs)

  • Parton distribution functions
  • W lepton asymmetry data


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