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An algebraic Ansatz for the proton's Poincar\'e-covariant wave function, which includes both scalar and pseudovector diquark correlations, is used to calculate proton valence, sea, and glue distribution functions (DFs). Regarding…

High Energy Physics - Phenomenology · Physics 2022-04-20 Lei Chang , Fei Gao , Craig D. Roberts

We compute the Parton Distribution Functions (PDFs) of the unpolarised muon for the leptons, the photon, the light quarks, and the gluon. We discuss in detail the issues stemming from the necessity of evaluating the strong coupling constant…

High Energy Physics - Phenomenology · Physics 2023-12-14 Stefano Frixione , Giovanni Stagnitto

I review the current status of the determination of helicity-dependent, or polarized, parton distribution functions from a comprehensive analysis of experimental data in perturbative quantum chromodynamics. I illustrate the latest…

High Energy Physics - Phenomenology · Physics 2016-03-23 Emanuele R. Nocera

Due to the presence of a large orbital angular momentum of the parton system produced at the early stage of non-central heavy-ion collisions, quarks and anti-quarks are shown to be polarized in the direction opposite to the reaction plane…

Nuclear Theory · Physics 2008-11-26 Zuo-tang Liang

We present a first global determination of spin-dependent parton distribution functions (PDFs) and their uncertainties using the NNPDF methodology: NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already used for the…

High Energy Physics - Phenomenology · Physics 2015-06-22 Emanuele R. Nocera , Richard D. Ball , Stefano Forte , Giovanni Ridolfi , Juan Rojo

We present the first simultaneous global QCD analysis of unpolarized transverse momentum dependent (TMD) and collinear parton distribution functions (PDFs) in the proton. Our study incorporates data from deep-inelastic scattering,…

High Energy Physics - Phenomenology · Physics 2025-10-16 P. C. Barry , A. Prokudin , T. Anderson , C. Cocuzza , L. Gamberg , W. Melnitchouk , E. Moffat , D. Pitonyak , J. -W. Qiu , N. Sato , A. Vladimirov , R. M. Whitehill

The STAR experiment at RHIC is carrying out a comprehensive high-energy spin physics program to understand the internal structure and dynamics of the proton in polarized proton-proton collisions at $\sqrt{s} = 200$ GeV and $\sqrt{s} =…

High Energy Physics - Experiment · Physics 2014-09-12 Xuan Li

We present a next-to-leading order QCD calculation of the cross section and longitudinal spin asymmetry in single-inclusive charged-lepton production, pp -> l X, at RHIC, where the lepton is produced in the decay of an electroweak gauge…

High Energy Physics - Phenomenology · Physics 2011-03-09 Daniel de Florian , Werner Vogelsang

Within the basis light-front quantization framework, we systematically investigate the unpolarized and longitudinally polarized double parton distributions (DPDs) of quarks inside the proton. We utilize the light-front wave functions of the…

High Energy Physics - Phenomenology · Physics 2025-07-11 Tian-Cai Peng , Zhi Hu , Sreeraj Nair , Siqi Xu , Xiang Liu , Chandan Mondal , Xingbo Zhao , James P. Vary

We study the production of $W^{\pm}$ and $Z$ gauge bosons in proton-proton and proton-neutron collisions up to a center-of-mass energy $\sqrt s=0.5\ TeV$, in connection with the realistic possibility of having proton-deuteron collisions at…

High Energy Physics - Phenomenology · Physics 2019-08-17 Claude Bourrely , Jacques Soffer

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 present a consistent calculation of the structure functions within a light-front constituent quark model of the nucleon. Relativistic effects and the relevance of the covariance constraints are analyzed for both polarized and unpolarized…

High Energy Physics - Phenomenology · Physics 2009-10-31 P. Faccioli , M. Traini , V. Vento

Preliminary results obtained by the COMPASS experiment for longitudinal-spin-dependent azimuthal asymmetries in single-hadron muoproduction off protons are presented for the first time. The analysis was carried out on the full data sample…

High Energy Physics - Experiment · Physics 2018-01-08 Bakur Parsamyan

Polarized parton distribution functions are determined by using asymmetry A_1 data from longitudinally polarized deep inelastic scattering experiments. From our \chi^2 analysis, polarized u-valence, d-valence, antiquark, and gluon…

High Energy Physics - Phenomenology · Physics 2017-08-23 M. Hirai

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

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

We present new functional form of pion and kaon fragmentation functions up to next-to-leading order obtained through a global fit to single-inclusive electron-positron annihilation data and also employ, the semi-inclusive deep inelastic…

High Energy Physics - Phenomenology · Physics 2019-03-08 M. Soleymaninia , A. N. Khorramian , S. M. Moosavi Nejad , F. Arbabifar

Quark contributions to the proton spin as deduced from polarized DIS of leptons off a nucleon target, and the octet baryon magnetic moments, can be used to deduce the antiquark polarizations $\Delta_{\overline{q}}$ inside the proton. In…

High Energy Physics - Phenomenology · Physics 2015-06-25 T. P. Cheng , Ling-Fong Li

Recent progress in the understanding of the nucleon is presented. The unpolarised structure functions are obtained with unprecedented precision from the combined H1 and ZEUS data and are used to extract proton parton distribution functions…

High Energy Physics - Experiment · Physics 2009-03-27 Cristinel Diaconu

We discuss the impact of recent high-statistics RHIC data on the determination of the gluon polarization in the proton in the context of a global QCD analysis of polarized parton distributions. We find clear evidence for a non-vanishing…

High Energy Physics - Phenomenology · Physics 2014-07-09 Daniel de Florian , Rodolfo Sassot , Marco Stratmann , Werner Vogelsang