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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

Traditional Bayesian approaches for model uncertainty quantification rely on notoriously difficult processes of marginalization over each network parameter to estimate its probability density function (PDF). Our hypothesis is that internal…

Machine Learning · Computer Science 2021-03-03 Rishabh Singh , Jose C. Principe

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 present an analysis of parton distribution functions (PDFs) of the proton using Markov Chain Monte Carlo (MCMC) methods. The MCMC approach naturally implements Bayes' theorem and thus provides a means to directly sample the underlying…

High Energy Physics - Phenomenology · Physics 2026-03-31 Peter Risse , Nasim Derakhshanian , Tomas Jezo , Karol Kovarik , Aleksander Kusina

The current scientific standard in PDF uncertainty estimation relies either on repeated fits over artificially generated data to arrive at Monte Carlo samples of best fits or on the Hessian method, which uses a quadratic expansion of the…

High Energy Physics - Phenomenology · Physics 2024-07-23 Peter Risse , Nasim Derakhshanian , Tomas Ježo , Karol Kovařík , Aleksander Kusina

An important limitation in current fits of parton distribution functions (PDFs) is that PDF uncertainties do not include any source of theoretical uncertainty. Here we present a general method for incorporating theoretical uncertainties…

High Energy Physics - Phenomenology · Physics 2018-10-05 R. L. Pearson , C. Voisey

Parton distribution functions (PDFs) form an essential part of particle physics calculations. Currently, the most precise predictions for these non-perturbative functions are generated through fits to global data. A problem that several PDF…

High Energy Physics - Phenomenology · Physics 2025-09-04 Mengshi Yan , Tie-Jiun Hou , Zhao Li , Kirtimaan Mohan , C. -P. Yuan

We present the MCscales approach for incorporating scale uncertainties in parton distribution functions (PDFs). The new methodology builds on the Monte Carlo sampling for propagating experimental uncertainties into the PDF space that…

High Energy Physics - Phenomenology · Physics 2023-03-27 Zahari Kassabov , Maria Ubiali , Cameron Voisey

In global QCD fits of parton distribution functions (PDFs), a large part of the estimated uncertainty on the PDFs originates from the choices of parametric functional forms and fitting methodology. We argue that these types of uncertainties…

High Energy Physics - Phenomenology · Physics 2023-02-21 Aurore Courtoy , Joey Huston , Pavel Nadolsky , Keping Xie , Mengshi Yan , C. -P. Yuan

We study the uncertainties of quantum mechanical observables, quantified by the standard deviation (square root of variance) in Haar-distributed random pure states. We derive analytically the probability density functions (PDFs) of the…

Quantum Physics · Physics 2022-07-22 Lin Zhang , Jinping Huang , Jiamei Wang , Shao-Ming Fei

We discuss the statistical properties of parton distributions within the framework of the NNPDF methodology. We present various tests of statistical consistency, in particular that the distribution of results does not depend on the…

Parton Distribution Functions (PDFs) play a central role in describing experimental data at colliders and provide insight into the structure of nucleons. As the LHC enters an era of high-precision measurements, a robust PDF determination…

High Energy Physics - Phenomenology · Physics 2026-01-21 Amedeo Chiefa , Luigi Del Debbio , Richard Kenway

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 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 present a new regression model for the determination of parton distribution functions (PDF) using techniques inspired from deep learning projects. In the context of the NNPDF methodology, we implement a new efficient computing framework…

High Energy Physics - Phenomenology · Physics 2019-09-04 Stefano Carrazza , Juan Cruz-Martinez

We review recent progress towards a determination of a set of polarized parton distributions from a global set of deep-inelastic scattering data based on the NNPDF methodology, in analogy with the unpolarized case. This method is designed…

High Energy Physics - Phenomenology · Physics 2010-11-19 J. Rojo , G. Ridolfi , R. D. Ball , V. Bertone , F. Cerutti , L. Del Debbio , S. Forte , A. Guffanti , J. I. Latorre , M. Ubiali

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

We present the determination of a set of parton distributions of the nucleon, at next-to-leading order, from a global set of deep-inelastic scattering data: NNPDF1.0. The determination is based on a Monte Carlo approach, with neural…

High Energy Physics - Phenomenology · Physics 2010-05-12 Richard D. Ball , Luigi Del Debbio , Stefano Forte , Alberto Guffanti , Jose I. Latorre , Andrea Piccione , Juan Rojo , Maria Ubiali

We continue to explore the hypothesis that neuronal populations represent and process analog variables in terms of probability density functions (PDFs). A neural assembly encoding the joint probability density over relevant analog variables…

Disordered Systems and Neural Networks · Physics 2007-05-23 M. J. Barber , J. W. Clark , C. H. Anderson

We present an investigation of the theoretical uncertainties in parton distribution functions (PDFs) due to missing higher-order corrections in the perturbative predictions used in the fit, and their relationship to the uncertainties in…

High Energy Physics - Phenomenology · Physics 2019-05-02 L. A. Harland-Lang , R. S. Thorne
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