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Focusing on hadron scattering at large partonic momentum fractions $x$, we compare nonperturbative QCD predictions for the asymptotic behavior of DIS structure functions and parton distribution functions (PDFs) to the $x$ and $Q$ dependence…

High Energy Physics - Phenomenology · Physics 2021-12-30 Aurore Courtoy , Pavel M. Nadolsky

We propose a new method to calculate parton distribution functions (PDFs) from lattice correlations of boosted quarks and gluons in the Coulomb gauge. Compared to the widely used gauge-invariant Wilson-line operators, these correlations…

High Energy Physics - Phenomenology · Physics 2024-04-30 Xiang Gao , Wei-Yang Liu , Yong Zhao

We present the first Monte Carlo based global QCD analysis of spin-averaged and spin-dependent parton distribution functions (PDFs) that includes nucleon isovector matrix elements in coordinate space from lattice QCD. We investigate the…

High Energy Physics - Phenomenology · Physics 2021-01-13 J. Bringewatt , N. Sato , W. Melnitchouk , Jian-Wei Qiu , F. Steffens , M. Constantinou

We point out a problem of the phenomenological definition of the valence partons as the difference between the partons and antipartons in the context of the NNLO evolution equations. After demonstrating that the classification of the parton…

High Energy Physics - Phenomenology · Physics 2020-10-14 Keh-Fei Liu

The results of our new QCD analysis of helicity parton distributions of the nucleon at full next-to-leading order (NLO) accuracy in the fixed-flavor number scheme will be presented. Performing a combined QCD fit on the global sets of latest…

High Energy Physics - Phenomenology · Physics 2014-02-12 Fatemeh Arbabifar , Ali N. Khorramian , Maryam Soleymaninia

The gradient-flow formalism provides a framework for the direct determination of moments of parton distribution functions (PDFs) from lattice QCD calculations. Their conversion from the gradient-flow scheme to $\overline{\text{MS}}$…

High Energy Physics - Phenomenology · Physics 2025-11-24 Robert V. Harlander , Jonas T. Kohnen , Andrea Shindler

We propose an analysis method for the leading-twist operator product expansion based lattice QCD determinations of the valence parton distribution function (PDF). In the first step, we determine the confidence-intervals of the leading-twist…

High Energy Physics - Lattice · Physics 2021-10-08 Nikhil Karthik , Raza Sabbir Sufian

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

It is common lore that Parton Distribution Functions (PDFs) in the $\overline{\rm { MS}}$ factorization scheme can become negative beyond leading order due to the collinear subtraction which is needed in order to define partonic cross…

High Energy Physics - Phenomenology · Physics 2020-12-30 Alessandro Candido , Stefano Forte , Felix Hekhorn

The results on polarized parton densities (PDFs) obtained using different methods of QCD analysis of the present polarized DIS data are discussed. Their dependence on the method used in the analysis, accounting or not for the kinematic and…

High Energy Physics - Phenomenology · Physics 2009-11-05 Elliot Leader , Aleksander V. Sidorov , Dimiter B. Stamenov

Parton distribution function (PDF) at small $x$ in a fast-moving proton is investigated within an upgraded parton model that includes parton splitting with branching cascades and parton fusion. In the region of moderately small $x$, we…

High Energy Physics - Phenomenology · Physics 2026-02-27 M. L. Nekrasov

We present a set of parton distribution functions (PDFs), based on the NNPDF2.3 set, which includes a photon PDF, and QED contributions to parton evolution. We describe the implementation of the combined QCD+QED evolution in the NNPDF…

Parton distribution functions (PDFs) are nonperturbative objects defined by nonlocal light-cone correlations. They cannot be computed directly from Quantum Chromodynamics (QCD). Using a standard lattice QCD approach, it is possible to…

High Energy Physics - Phenomenology · Physics 2017-02-08 Alessandro Bacchetta , Marco Radici , Barbara Pasquini , Xiaonu Xiong

Within the theory of Quantum Chromodynamics (QCD), the rich structure of hadrons can be quantitatively characterized, among others, using a basis of universal non-perturbative functions: parton distribution functions (PDFs), generalized…

High Energy Physics - Lattice · Physics 2019-06-14 Krzysztof Cichy , Martha Constantinou

We investigate the behavior of spin-dependent parton distribution functions (PDFs) at large parton momentum fractions x in the context of global QCD analysis. We explore the constraints from existing deep-inelastic scattering data, and from…

High Energy Physics - Phenomenology · Physics 2015-06-19 P. Jimenez-Delgado , H. Avakian , W. Melnitchouk

We present LO, NLO and NNLO sets of parton distribution functions (PDFs) of the proton determined from global analyses of the available hard scattering data. These MMHT2014 PDFs supersede the `MSTW2008' parton sets, but are obtained within…

High Energy Physics - Phenomenology · Physics 2015-06-11 L. A. Harland-Lang , A. D. Martin , P. Motylinski , R. S. Thorne

We present the first lattice results on isovector unpolarized and longitudinally polarized parton distribution functions (PDFs) at physical pion mass. The PDFs are obtained using the large-momentum effective field theory (LaMET) framework…

High Energy Physics - Lattice · Physics 2018-09-12 Huey-Wen Lin , Jiunn-Wei Chen , Tomomi Ishikawa , Jian-Hui Zhang

An explicit evaluation of the double parton distribution functions (dPDFs), within a relativistic Light-Front approach to constituent quark models, is presented. dPDFs encode information on the correlations between two partons inside a…

High Energy Physics - Phenomenology · Physics 2015-06-22 Matteo Rinaldi , Sergio Scopetta , Marco Traini , Vicente Vento

We provide an analysis of the x-dependence of the bare unpolarized, helicity and transversity iso-vector parton distribution functions (PDFs) from lattice calculations employing (maximally) twisted mass fermions. The x-dependence of the…

We present preliminary results on the determination of spin-dependent, or polarised, Parton Distribution Functions (PDFs) from all relevant inclusive polarised DIS data. The analysis is performed within the NNPDF approach, which provides a…

High Energy Physics - Phenomenology · Physics 2012-06-26 Emanuele R. Nocera , Stefano Forte , Giovanni Ridolfi , Juan Rojo