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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

The full exploitation of the increasingly precise LHC measurements is essential in order to reduce the uncertainty of theoretical predictions at hadron colliders. The NNPDF2.3 fit was the first PDF determination including the effect of the…

High Energy Physics - Phenomenology · Physics 2014-07-14 Maria Ubiali

We present a new public code, FPPDF, to perform global fits of parton distribution functions (PDFs). The fitting methodology follows that implemented by the MSHT collaboration, namely applying a fixed polynomial parameterisation of the PDFs…

High Energy Physics - Phenomenology · Physics 2026-02-10 J. M. Cruz-Martinez , T. Giani , L. A. Harland-Lang

A "meta-analysis" is a method for comparison and combination of nonperturbative parton distribution functions (PDFs) in a nucleon obtained with heterogeneous procedures and assumptions. Each input parton distribution set is converted into a…

High Energy Physics - Phenomenology · Physics 2015-06-18 Jun Gao , Pavel Nadolsky

An extension of the xFitter open-source program for QCD analyses is presented, allowing for a polynomial parameterization of the dependence of physical observables on theoretical parameters. This extension enables simultaneous determination…

High Energy Physics - Phenomenology · Physics 2024-12-03 XiaoMin Shen , Simone Amoroso , Jun Gao , Katerina Lipka , Oleksandr Zenaiev

We systematically explore the parametrization dependence of the Parton Distribution Functions (PDFs) to better quantify the true uncertainty from global QCD analyses. To achieve this, we employ a novel technique that automates the…

High Energy Physics - Phenomenology · Physics 2025-11-20 Lucas Kotz , Aurore Courtoy , Pavel Nadolsky , Fredrick Olness , Maximiliano Ponce-Chavez

We compare the cross section for exclusive $J/\psi$ photoproduction calculated at NLO in the collinear factorization approach with HERA and LHCb data. Using the optimum scale formalism together with the subtraction of the low $k_t<Q_0$…

High Energy Physics - Phenomenology · Physics 2020-05-20 Chris A. Flett , Stephen P. Jones , Alan D. Martin , Misha G. Ryskin , Thomas Teubner

Previously published data on inclusive neutral and charged current e+p and e-p deep inelastic scattering from HERA have been combined. The new, model-independent method of combining the measured cross sections takes full account of…

High Energy Physics - Experiment · Physics 2015-05-13 C. Gwenlan

Quantitatively connecting properties of parton distribution functions (PDFs, or parton densities) to the theoretical assumptions made within the QCD analyses which produce them has been a longstanding problem in HEP phenomenology. To…

High Energy Physics - Phenomenology · Physics 2024-07-08 Brandon Kriesten , Jonathan Gomprecht , T. J. Hobbs

We introduce the Hessian reweighting of parton distribution functions (PDFs). Similarly to the better-known Bayesian methods, its purpose is to address the compatibility of new data and the quantitative modifications they induce within an…

High Energy Physics - Phenomenology · Physics 2015-06-18 Hannu Paukkunen , Pia Zurita

The high-precision HERA data can be used as an input to a QCD analysis within the DGLAP formalism to obtain the detailed description of the proton structure in terms of the parton distribution functions (PDFs). However, when searching for…

High Energy Physics - Phenomenology · Physics 2016-06-22 Oleksii Turkot , Katarzyna Wichmann , Aleksander Filip Zarnecki

We present a new set of parton distribution functions (PDFs) based on a fully global dataset and machine learning techniques: NNPDF4.0. We expand the NNPDF3.1 determination with 44 new datasets, mostly from the LHC. We derive a novel…

Parton distribution functions (PDFs) play a central role in calculations for the Large Hadron Collider (LHC). To gain a deeper understanding of the emergence and interplay of constraints on the PDFs in the global QCD analyses, it is…

We use the nCTEQ analysis framework to investigate nuclear Parton Distribution Functions (nPDFs) in the region of large x and intermediate-to-low $Q$, with special attention to recent JLab Deep Inelastic Scattering data on nuclear targets.…

We discuss the current minimisation strategies adopted by research projects involving the determination of parton distribution functions (PDFs) and fragmentation functions (FFs) through the training of neural networks. We present a short…

High Energy Physics - Phenomenology · Physics 2017-11-29 Stefano Carrazza , Nathan P. Hartland

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…

We perform the next-to-next-leading-order (NNLO) QCD global fit of PDFs using inclusive charged-lepton and neutrino DIS data down to Q = 1 GeV. We also consider the data on neutrino-nucleon dimuon production, that allows us to disentangle…

High Energy Physics - Phenomenology · Physics 2008-10-28 S. Alekhin , S. Kulagin , R. Petti

In this talk, I present the brand new results from the H1 and ZEUS Collaborations on the combination of all previously published inclusive deep inelastic cross sections at HERA for neutral and charged current $e^\pm p$ scattering for zero…

High Energy Physics - Experiment · Physics 2015-11-18 Zhiqing Zhang

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

We discuss a test of the generalization power of the methodology used in the determination of parton distribution functions (PDFs). The "future test" checks whether the uncertainty on PDFs, in regions in which they are not constrained by…

High Energy Physics - Phenomenology · Physics 2021-04-21 Juan Cruz-Martinez , Stefano Forte , Emanuele R. Nocera