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We discuss a Bayesian methodology for the solution of the inverse problem underlying the determination of parton distribution functions (PDFs). In our approach, Gaussian Processes (GPs) are used to model the PDF prior, while Bayes theorem…

High Energy Physics - Phenomenology · Physics 2024-07-03 Alessandro Candido , Luigi Del Debbio , Tommaso Giani , Giacomo Petrillo

Within the Dyson-Schwinger equation formulation of QCD, a rainbow ladder truncation is used to calculate the pion valence-quark distribution function(PDF). The gap equation is renormalized at a typical hadronic scale, of order 0.5GeV, which…

Nuclear Theory · Physics 2015-09-30 Lei Chang , Anthony W. Thomas

We present a lattice QCD determination of the Mellin moments of the unpolarized gluon parton distribution function in the proton. The analysis is based on matrix elements of nonlocal gluon operators coupled to momentum-boosted proton…

High Energy Physics - Lattice · Physics 2026-05-29 Joseph Delmar , Krzysztof Cichy , Martha Constantinou , Yong Zhao

In global PDF analyses, parton distribution functions (PDFs) are parametrised at a fixed input scale $Q_0$ and evolved to higher scales using the DGLAP equations. Since QCD evolution is fully determined within perturbation theory, the…

High Energy Physics - Phenomenology · Physics 2025-11-13 Ivan A. Godino , Eva D. Z. Groenendijk , Tanjona R. Rabemananjara

We compute the second moments of pion and rho parton distribution functions (PDFs) in lattice QCD with $N_f = 2+1$ flavors of improved Wilson fermions. We determine both singlet and non-singlet flavor combinations and, for the first time,…

High Energy Physics - Lattice · Physics 2022-02-02 Marius Löffler , Philipp Wein , Thomas Wurm , Simon Weishäupl , Daniel Jenkins , Rudolf Rödl , Andreas Schäfer , Lisa Walter

We calculate the valence parton distribution function~(PDF) of pion, within the theoretical approach based on spectral function representation of valence quarks in the pion. In this approach we assume that the soft partonic structure of…

High Energy Physics - Phenomenology · Physics 2026-03-16 Joseph Maerovitz , Christopher Leon , Misak Sargsian

We review the latest progress in lattice QCD calculations of the partonic structure of hadrons. This structure is, in particular, described in terms of $x$-dependent distributions, the simplest of which are the standard parton distribution…

High Energy Physics - Lattice · Physics 2021-10-18 Krzysztof Cichy

We present a lattice QCD study of valence parton distribution inside the pion within the framework of Large Momentum Effective Theory. We use a mixed action approach with 1-HYP smeared valence Wilson clover quarks on 2+1 flavor HISQ sea…

Using the approach proposed a few years ago by X. Ji, it has become feasible to extract parton distribution functions (PDFs) from lattice QCD, a task thought to be extremely difficult before Ji's proposal. In this talk, we discuss this…

We explore the role of parametrizations for nonperturbative QCD functions in global analyses, with a specific application to extending a phenomenological analysis of the parton distribution functions (PDFs) in the charged pion realized in…

High Energy Physics - Phenomenology · Physics 2024-04-17 Lucas Kotz , Aurore Courtoy , Pavel Nadolsky , Fredrick Olness , Maximiliano Ponce-Chavez

We present a calculation of the pion valence quark distribution extracted using the formalism of reduced Ioffe time pseudo-distributions or more commonly known as pseudo-PDFs. Our calculation is carried out on two different 2+1 flavor QCD…

We present recent results on the first moments of parton distributions using gauge configurations generated with two degenerate flavors of light twisted mass quarks with pion mass fixed approximately to its physical value. We also present a…

High Energy Physics - Lattice · Physics 2016-04-20 Constantia Alexandrou

We evaluate the valence double parton distribution (dPDF) of the pion in the Nambu--Jona-Lasinio model. At the low-energy quark-model scale and in the chiral limit a particularly simple factorized form $D(x_1,x_2, \vec{q}) =…

High Energy Physics - Phenomenology · Physics 2020-01-06 Wojciech Broniowski , Enrique Ruiz Arriola

We review the current status of spin-averaged and spin-dependent parton distribution functions (PDFs) of the nucleon. After presenting the formalism used to fit PDFs in modern global data analyses, we discuss constraints placed on the PDFs…

High Energy Physics - Phenomenology · Physics 2015-06-16 P. Jimenez-Delgado , W. Melnitchouk , J. F. Owens

The interest into parton distribution functions (PDFs) and fragmentation functions (FFs) in current high energy physics research is twofold. On the one hand, they are fundamental objects to conduct precision phenomenology studies, e.g. at…

High Energy Physics - Phenomenology · Physics 2025-09-22 Tanishq Sharma

Parton distribution functions (PDFs) and light-cone distribution amplitudes (LCDAs) are central non-perturbative objects of interest in high-energy inelastic and elastic scattering, respectively. As a result, an ab-initio determination of…

High Energy Physics - Lattice · Physics 2021-10-22 William Detmold , Anthony V. Grebe , Issaku Kanamori , C. -J. David Lin , Robert J. Perry , Yong Zhao

We present the first lattice-QCD $x$-dependent pion valence-quark generalized parton distribution (GPD) calculated directly at physical pion mass using the Large-Momentum Effective Theory (LaMET) with next-to-next-to-leading order…

High Energy Physics - Lattice · Physics 2023-10-17 Huey-Wen Lin

We review basic ideas and recent developments on the determination of the parton substructure of the nucleon, in view of applications to precision hadron collider physics. We review the way information on parton distributions (PDFs) is…

High Energy Physics - Phenomenology · Physics 2015-03-17 Stefano Forte

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

We investigate the parton-distribution functions (PDFs) for the positively charged pion and kaon at a low-renormalization scale ~ 1 GeV. To this end, we employ the gauge-invariant effective chiral action from the nonlocal chiral-quark…

High Energy Physics - Phenomenology · Physics 2013-05-30 Seung-il Nam