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Parton distribution functions (PDFs) form an essential part of particle physics calculations. Currently, the most precise predictions for these non-perturbative functions are generated through fits to global data. A problem that several PDF…

High Energy Physics - Phenomenology · Physics 2025-09-04 Mengshi Yan , Tie-Jiun Hou , Zhao Li , Kirtimaan Mohan , C. -P. Yuan

The high precision and large kinematic coverage of the data from the HERA-I running period (1994-2000) have already allowed precise extractions of proton parton distribution functions. The HERA-II running program is now underway and is…

High Energy Physics - Phenomenology · Physics 2009-11-11 C. Gwenlan , A. Cooper-Sarkar , C. Targett-Adams

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 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

We present the main results of our recent papers, where we derived an analytical solution of the QCD evolution equations for parton distribution functions. The valence and non-singlet quark components satisfy the Gross-Llewellyn-Smith and…

High Energy Physics - Phenomenology · Physics 2025-10-24 A. V. Kotikov , A. V. Lipatov

A phenomenological study of the final combined HERA data on inclusive deep inelastic scattering (DIS) has been performed. The data are presented and investigated for a kinematic range extending from values of the four-momentum transfer,…

High Energy Physics - Experiment · Physics 2017-08-02 I. Abt , A. M. Cooper-Sarkar , B. Foster , V. Myronenko , K. Wichmann , M. Wing

In this article we present a review of the structure of the proton and the current status of our knowledge of the parton distribution functions (PDFs). The lepton-nucleon scattering experiments which provide the main constraints in PDF…

High Energy Physics - Experiment · Physics 2013-03-20 Emmanuelle Perez , Eram Rizvi

An extension of the xFitter open-source program for QCD analyses is presented, allowing for a polynomial parameterization of the dependence of physical observables on theoretical parameters. This extension enables simultaneous determination…

High Energy Physics - Phenomenology · Physics 2024-12-03 XiaoMin Shen , Simone Amoroso , Jun Gao , Katerina Lipka , Oleksandr Zenaiev

We review recent progress in the determination of the parton distribution functions (PDFs) of the proton, with emphasis on the applications for precision phenomenology at the Large Hadron Collider (LHC). First of all, we introduce the…

High Energy Physics - Phenomenology · Physics 2018-05-23 Jun Gao , Lucian Harland-Lang , Juan Rojo

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

The H1 and ZEUS experiments are measuring diffractive interactions in ep collisions at HERA. Performing QCD fits of these data with NLO DGLAP, diffractive parton distribution functions can be calculated. These diffractive PDFs can be used…

High Energy Physics - Experiment · Physics 2007-05-23 Isabell-Alissandra Melzer-Pellmann

Recent measurements of inclusive and semi-inclusive deep inelastic scattering in electron-proton collisions at HERA are reviewed. These measurements are used to determine the parton distribution functions (PDFs) of the proton, a necessary…

High Energy Physics - Experiment · Physics 2019-08-14 K. Lipka

In the first chapter we give an introduction to hard diffractive scattering in QCD to introduce basic concepts and terminology. In the second chapter we make predictions for the evolution of skewed parton distributions in a proton in the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Andreas Freund

We present a global analysis of available data on inclusive structure functions measured in electron-proton scattering at small values of Bjorken-x, including the latest data from the combined HERA analysis on reduced cross sections. Our…

High Energy Physics - Phenomenology · Physics 2015-05-28 Paloma Quiroga-Arias , Javier L. Albacete , Nestor Armesto , Jose Guilherme Milhano , Carlos A. Salgado

Next-to-leading order QCD analyses of the ZEUS data on deep inelastic scattering together with fixed-target data have been perfomed, from which the gluon and the quark densities of the proton and the value of the strong coupling constant,…

High Energy Physics - Experiment · Physics 2012-08-27 ZEUS Collaboration

The combination is presented of all inclusive deep inelastic scattering cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current $ep$ scattering for zero beam polarisation. The data were…

High Energy Physics - Experiment · Physics 2016-07-05 M. Wing

We present our QCD analysis of the proton structure function $F_2^p(x,Q^2)$ to determine the parton distributions at the next-to-leading order (NLO). The heavy quark contributions to $F_2^i(x,Q^2)$, with $i$ = $c$, $b$ have been included in…

High Energy Physics - Phenomenology · Physics 2015-06-05 H. Khanpour , Ali N. Khorramian , S. Atashbar Tehrani

We provide an assessment of the state of the art in various issues related to experimental measurements, phenomenological methods and theoretical results relevant for the determination of parton distribution functions (PDFs) and their…

Over the last two decades, the HERA collider has provided a large amount of new information about QCD dynamics at high energy. While the most appreciated are the measurements of the proton structure functions in a wide range of parton…

High Energy Physics - Experiment · Physics 2009-10-02 Halina Abramowicz

A new parametrization for the parton distribution functions with a higher flexibility in the small-$x$ region is presented. It has been implemented in the xFitter open-source PDF fitting tool, and compared to the default xFitter…

High Energy Physics - Phenomenology · Physics 2019-06-26 Francesco Giuli , Marco Bonvini