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We study the correlation between different sets of parton distributions (PDFs). Specifically, viewing different PDF sets as distinct determinations, generally correlated, of the same underlying physical quantity, we examine the extent to…

High Energy Physics - Phenomenology · Physics 2021-12-09 Richard D. Ball , Stefano Forte , Roy Stegeman

We show how to account for correlations between theoretical uncertainties incorporated in parton distribution function (PDF) fits, and the theoretical uncertainties in the predictions made using these PDFs. We demonstrate by explicit…

High Energy Physics - Phenomenology · Physics 2021-10-04 Richard D. Ball , Rosalyn L. Pearson

We investigate the Monte Carlo approach to propagation of experimental uncertainties within the context of the established "MSTW 2008" global analysis of parton distribution functions (PDFs) of the proton at next-to-leading order in the…

High Energy Physics - Phenomenology · Physics 2012-08-13 G. Watt , R. S. Thorne

We discuss the determination of the parton substructure of hadrons by casting it as a peculiar form of pattern recognition problem in which the pattern is a probability distribution, and we present the way this problem has been tackled and…

High Energy Physics - Phenomenology · Physics 2020-08-31 Stefano Forte , Stefano Carrazza

We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on…

High Energy Physics - Phenomenology · Physics 2013-04-01 The NNPDF Collaboration , Richard D. Ball , Stefano Forte , Alberto Guffanti , Emanuele R. Nocera , Giovanni Ridolfi , Juan Rojo

A thorough understanding of the issues surrounding the determination of parton distributions is crucial due to their importance to calculations of LHC observables. However, it is still not fully understood how much of an impact…

High Energy Physics - Phenomenology · Physics 2014-09-16 Christopher S. Deans

We present the software framework underlying the NNPDF4.0 global determination of parton distribution functions (PDFs). The code is released under an open source licence and is accompanied by extensive documentation and examples. The code…

The publication by Gagunashvili [arXiv:1011.0662] suffers from several caveats: i) The method is based upon the false assumption that the median of chi square distributed random variables is chi square distributed. ii) The information…

Data Analysis, Statistics and Probability · Physics 2012-09-11 G. Bohm , G. Zech

A set of quasi-parton distribution functions (quasi-PDFs) have been recently proposed by Ji. Defined as the matrix elements of equal-time spatial correlations, they can be computed on the lattice and should reduce to the standard PDFs when…

High Energy Physics - Phenomenology · Physics 2015-03-03 Leonard Gamberg , Zhong-Bo Kang , Ivan Vitev , Hongxi Xing

A determination of Parton Distribution Functions (PDFs) from a global fit to a dataset including measurements from the LHC has been performed. The determinations have been carried out according to the NNPDF methodology, leading to a fit…

High Energy Physics - Phenomenology · Physics 2014-11-04 Nathan Hartland

We present a new set of parton distributions, NNPDF3.1, which updates NNPDF3.0, the first global set of PDFs determined using a methodology validated by a closure test. The update is motivated by recent progress in methodology and available…

Parton Distribution Functions (PDFs) are a key ingredient in theoretical predictions for Large Hadron Collider (LHC) observables and play a central role in the extraction of precision Standard Model (SM) and Beyond the SM (BSM) parameters…

High Energy Physics - Phenomenology · Physics 2026-03-02 Richard D. Ball , Tommaso Giani , Felix Hekhorn , Jaco ter Hoeve , Tanjona R. Rabemananjara , Juan Rojo , Roy Stegeman , Maria Ubiali

We present NNPDF3.0, the first set of parton distribution functions (PDFs) determined with a methodology validated by a closure test. NNPDF3.0 uses a global dataset including HERA-II deep-inelastic inclusive cross-sections, the combined…

A recent study by Wang {\it et al.}(arXiv:2309.01417) proposed a novel connection between the nature of the parton distribution function (PDF) and the characteristics of its moments. In this study, we apply these findings to analyze the…

High Energy Physics - Phenomenology · Physics 2024-07-16 Xiaobin Wang , Zexin Wu , Minghui Ding , Lei Chang

Accurate Standard Model predictions of proton-proton collisions are essential for interpreting the current and forthcoming experimental measurements from high-energy colliders. The quest for physics beyond the Standard Model is in fact…

High Energy Physics - Phenomenology · Physics 2025-04-09 Giacomo Magni

We present the first unbiased determination of spin-dependent, or polarized, Parton Distribution Functions (PDFs) of the proton. A statistically sound representation of the corresponding uncertainties is achieved by means of the NNPDF…

High Energy Physics - Phenomenology · Physics 2014-03-04 Emanuele Roberto Nocera

We examine the dependence of parton distribution functions (PDFs) on the value of the QCD coupling strength $\alpha_{s}(M_{Z})$. We explain a simple method that is rigorously valid in the quadratic approximation normally applied in PDF…

High Energy Physics - Phenomenology · Physics 2014-11-20 Hung-Liang Lai , Joey Huston , Zhao Li , Pavel Nadolsky , Jon Pumplin , Daniel Stump , C. -P. Yuan

We consider the generic problem of performing a global fit to many independent data sets each with a different overall multiplicative normalization uncertainty. We show that the methods in common use to treat multiplicative uncertainties…

High Energy Physics - Phenomenology · Physics 2010-06-02 The NNPDF Collaboration , Richard D. Ball , Luigi Del Debbio , Stefano Forte , Alberto Guffanti , Jose I. Latorre , Juan Rojo , Maria Ubiali

We critically assess the robustness of uncertainties on parton distribution functions (PDFs) determined using neural networks from global sets of experimental data collected from multiple experiments. We view the determination of PDFs as an…

High Energy Physics - Phenomenology · Physics 2025-03-25 Andrea Barontini , Mark N. Costantini , Giovanni De Crescenzo , Stefano Forte , Maria Ubiali

We present new sets of nuclear parton distribution functions (nPDFs) at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). Our analyses are based on deeply inelastic scattering data with charged-lepton and neutrino beams…

High Energy Physics - Phenomenology · Physics 2019-12-17 Marina Walt , Ilkka Helenius , Werner Vogelsang