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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

We present a first machine learning-based decoding of the gluonic structure of the proton from lattice QCD using a variational autoencoder inverse mapper (VAIM). Harnessing the power of generative AI, we predict the parton distribution…

High Energy Physics - Phenomenology · Physics 2025-07-25 Brandon Kriesten , Alex NieMiera , William Good , T. J. Hobbs , Huey-Wen Lin

We present a first determination of the nuclear parton distribution functions (nPDF) based on the NNPDF methodology: nNNPDF1.0. This analysis is based on neutral-current deep-inelastic structure function data and is performed up to NNLO in…

High Energy Physics - Phenomenology · Physics 2019-07-23 Rabah Abdul Khalek , Jacob J. Ethier , Juan Rojo

We present a high-statistics lattice-QCD determination of the kaon gluon parton distribution function and gluon momentum fraction. We use clover valence fermion action to take 1,296,640 kaon-correlator measurements on a HISQ ensemble with…

High Energy Physics - Lattice · Physics 2025-06-30 Alex NieMiera , William Good , Huey-Wen Lin

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…

In this document, we summarize the status and challenges of calculating parton physics in lattice QCD for the US Particle Physics Community Planning Exercise (a.k.a. "Snowmass"). While PDF-moments calculations have been very successful and…

We present the first lattice calculation of the nucleon isovector unpolarized generalized parton distribution (GPD) at the physical pion mass using a lattice ensemble with 2+1+1 flavors of highly improved staggered quarks (HISQ) generated…

High Energy Physics - Phenomenology · Physics 2021-11-10 Huey-Wen Lin

We perform a comprehensive global QCD analysis of spin-dependent parton distribution functions (PDFs), combining all available data on inclusive and semi-inclusive deep-inelastic scattering (DIS), as well as inclusive weak boson and jet…

High Energy Physics - Phenomenology · Physics 2025-12-11 C. Cocuzza , N. T. Hunt-Smith , W. Melnitchouk , N. Sato , A. W. Thomas

We present a lattice-QCD calculation of the unpolarized isovector parton distribution function (PDF) using ensembles at the physical pion mass with large proton boost momenta $P_z \in \{2.2,2.6,3.0\}$~GeV within the framework of…

High Energy Physics - Lattice · Physics 2018-05-21 Jiunn-Wei Chen , Luchang Jin , Huey-Wen Lin , Yu-Sheng Liu , Yi-Bo Yang , Jian-Hui Zhang , Yong Zhao

The strong force which binds hadrons is described by the theory of quantum chromodynamics (QCD). Determining the character and manifestations of QCD is one of the most important and challenging outstanding issues necessary for a…

High Energy Physics - Lattice · Physics 2025-06-06 Huey-Wen Lin

The quasi-PDF approach provides a path to computing parton distribution functions (PDFs) using lattice QCD. This approach requires matrix elements of a power-divergent operator in a nucleon at high momentum and one generically expects…

We critically examine uncertainties in parton distribution functions (PDFs) at large x arising from nuclear effects in deuterium F2 structure function data. Within a global PDF analysis, we assess the impact on the PDFs from uncertainties…

High Energy Physics - Phenomenology · Physics 2011-08-17 A. Accardi , W. Melnitchouk , J. F. Owens , M. E. Christy , C. E. Keppel , L. Zhu , J. G. Morfin

Perturbative quantum chromodynamics (QCD) ceases to be applicable at low interaction energies due to the rapid increase of the strong coupling. In that limit, the non-perturbative regime determines the properties of quarks and gluons…

High Energy Physics - Phenomenology · Physics 2021-10-06 Rabah Abdul Khalek

We present the first open-source analysis of parton distribution functions (PDFs) of charged pions using xFitter, an open-source QCD fit framework to facilitate PDF extraction and analyses. Our calculations are implemented at…

Heavy quark parton distribution functions (PDFs) play an important role in several Standard Model and New Physics processes. Most analyses rely on the assumption that the charm and bottom PDFs are generated perturbatively by gluon splitting…

High Energy Physics - Phenomenology · Physics 2016-08-08 Florian Lyonnet , Aleksander Kusina , Tomáš Ježo , Karol Kovařík , Fred Olness , Ingo Schienbein , Ji-Young Yu

We present a nonperturbative determination of the pion valence parton distribution function (PDF) moment ratios $\left\langle x^{n-1} \right\rangle / \left\langle x \right\rangle$ up to $n=6$, using the gradient flow in lattice QCD. As a…

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 present the first unbiased determination of spin-dependent, or polarized, Parton Distribution Functions (PDFs) of the proton. A statistically sound representation of the corresponding uncertainties is achieved by means of the NNPDF…

High Energy Physics - Phenomenology · Physics 2014-03-04 Emanuele Roberto Nocera

Building upon the PDFSense framework developed in Ref. [1], we perform a comprehensive analysis of the sensitivity of present and future high-energy data to a number of quantities commonly evaluated in lattice gauge theory, with a…

High Energy Physics - Phenomenology · Physics 2021-06-15 T. J. Hobbs , Bo-Ting Wang , Pavel M. Nadolsky , Fredrick I. Olness

We perform the first global QCD analysis of parton distribution functions (PDFs) in the pion, combining $\pi A$ Drell-Yan data with leading neutron electroproduction from HERA within a Monte Carlo approach based on nested sampling.…

High Energy Physics - Phenomenology · Physics 2018-10-17 P. C. Barry , N. Sato , W. Melnitchouk , Chueng-Ryong Ji