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Modern global analyses of the structure of the proton include collider measurements which probe energies well above the electroweak scale. While these provide powerful constraints on the parton distribution functions (PDFs), they are also…

High Energy Physics - Phenomenology · Physics 2019-10-02 Stefano Carrazza , Celine Degrande , Shayan Iranipour , Juan Rojo , Maria Ubiali

We present numerical studies of the leading non-linear corrections to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations of parton distribution functions (PDFs) resulting from gluon recombination. The effect of these…

High Energy Physics - Phenomenology · Physics 2023-12-21 Pit Duwentäster , Vadim Guzey , Ilkka Helenius , Hannu Paukkunen

In this paper polarized valon distribution is derived from unpolarized valon distribution. In driving polarized valon distribution some unknown parameters exist which must be determined by fitting to experimental data. Here we have used…

High Energy Physics - Phenomenology · Physics 2007-05-23 Ali N. Khorramian , A. Mirjalili , S. Atashbar Tehrani

We present the new MSHT20 set of parton distribution functions (PDFs) of the proton, determined from global analyses of the available hard scattering data. The PDFs are made available at NNLO, NLO, and LO, and supersede the MMHT14 sets.…

High Energy Physics - Phenomenology · Physics 2022-08-22 S. Bailey , T. Cridge , L. A. Harland-Lang , A. D. Martin , R. S. Thorne

We have presented the results of our next-to-next-to-leading order (NNLO) QCD analysis of nuclear parton distribution functions (nuclear PDFs) [Phys. Rev. D 93 (2016) 014026, arXiv:1601.00939 [hep-ph]] using all available neutral current…

High Energy Physics - Phenomenology · Physics 2020-12-17 S. Atashbar Tehrani

Polarized parton distributions and structure functions of the nucleon are analyzed in the improved valon model. The valon representation provides a model to represent hadrons in terms of quarks, providing a unified description of bound…

High Energy Physics - Phenomenology · Physics 2009-11-10 Ali N. Khorramian , A. Mirjalili , S. Atashbar Tehrani

We present a first lattice QCD calculation of the unpolarized nucleon's isovector transverse-momentum-dependent parton distribution functions (TMDPDFs), which are essential to predict observables of multi-scale, semi-inclusive processes in…

Parton distribution functions (PDFs) describe universal properties of bound states and allow us to calculate scattering amplitudes in processes with large momentum transfer. Calculating PDFs involves the evaluation of matrix elements with a…

High Energy Physics - Lattice · Physics 2025-02-10 Mari Carmen Bañuls , Krzysztof Cichy , C. -J. David Lin , Manuel Schneider

At large values of x the parton distribution functions (PDFs) of the proton are poorly constrained and there are considerable variations between different global fits. Data at such high x have already been published by the ZEUS…

High Energy Physics - Experiment · Physics 2020-07-01 ZEUS Collaboration

We investigate the nucleon and pion gluon distribution functions in the framework of holographic QCD, focusing on the small Bjorken x region. Based on an approximate relation, the gluon distributions are extracted from structure functions…

High Energy Physics - Phenomenology · Physics 2020-06-24 Akira Watanabe , Takahiro Sawada , Mei Huang

We study the cross section \sigma and Forward-Backward asymmetry A_{FB} in the process pp \to \gamma^*,Z \to \ell^+\ell^- (with \ell=e,\mu) for determinations of Parton Distribution Functions (PDFs) of the proton. We show that, once mapped…

High Energy Physics - Phenomenology · Physics 2019-03-19 E. Accomando , J. Fiaschi , F. Hautmann , S. Moretti

We discuss the bounds on polarized parton distributions which follow from their definition in terms of cross section asymmetries. We spell out how the bounds obtained in the naive parton model can be derived within perturbative QCD at…

High Energy Physics - Phenomenology · Physics 2023-12-14 Guido Altarelli , Stefano Forte , Giovanni Ridolfi

An updated next-to-leading order (NLO) QCD analysis of the spin asymmetries A_1^N(x,Q^2) and parton distributions delta f(x,Q^2) in longitudinally polarized deep-inelastic lepton-nucleon scattering is presented within the framework of the…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. Stratmann

We perform a global QCD analysis of the pion electromagnetic form factor (FF) data from pion electroproduction and elastic pion scattering to extract the valence pion generalized parton distributions (GPDs) at zero skewness. The analysis…

High Energy Physics - Phenomenology · Physics 2025-12-30 The MMGPDs Collaboration , Muhammad Goharipour , M. H. Amiri , Fatemeh Irani , Hadi Hashamipour , K. Azizi

Effects of the spin-dependent gluon distributions on J/$\psi$ productions in polarized ep and pp collisions are investigated. These productions serve as a very clean probe of the spin-dependent gluon distributions in a proton.

High Energy Physics - Phenomenology · Physics 2009-09-25 T. Morii , S. Tanaka , T. Yamanishi

We present progress towards the first unpolarized gluon quasi-PDF from lattice QCD using high-statistics measurement with $a \approx 0.12$ fm and two valence pion masses $M_\pi \approx 310$ and $690$ MeV generated on $2+1+1$-flavors of HISQ…

High Energy Physics - Lattice · Physics 2024-09-05 William Good , Kinza Hasan , Huey-Wen Lin

We review the current state of the art in the determination of the parton substructure of the nucleon, as expressed in terms of parton distribution functions (PDFs), and probed in high-energy lepton-hadron and hadron-hadron collisions, and…

High Energy Physics - Phenomenology · Physics 2013-10-23 Stefano Forte , Graeme Watt

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

Supposing there exists an effective charge which defines an evolution scheme for both unpolarised and polarised parton distribution functions (DFs) that is all-orders exact and using Ans\"atze for hadron-scale proton polarised valence quark…

High Energy Physics - Phenomenology · Physics 2023-08-09 Peng Cheng , Yang Yu , Hui-Yu Xing , Chen Chen , Zhu-Fang Cui , Craig D. Roberts

The recent high precision SMC data on polarized $\mu p$ scatterings have again confirmed that very little of the proton spin is carried by quarks. To unravel the mystery of the proton spin structure, it is quite important to know the…

High Energy Physics - Phenomenology · Physics 2009-10-28 T. Morii , S. Tanaka , T. Yamanishi
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