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We determine the strong coupling alpha_s at NNLO in perturbative QCD using the global dataset input to the NNPDF2.1 NNLO parton fit: data from neutral and charged current deep-inelastic scattering, Drell-Yan, vector boson production and…

High Energy Physics - Phenomenology · Physics 2015-05-30 Richard D. Ball , Valerio Bertone , Luigi Del Debbio , Stefano Forte , Alberto Guffanti , Jose I. Latorre , Simone Lionetti , Juan Rojo , Maria Ubiali

We present a method developed by the NNPDF Collaboration that allows the inclusion of new experimental data into an existing set of parton distribution functions without the need for a complete refit. A Monte Carlo ensemble of PDFs may be…

High Energy Physics - Phenomenology · Physics 2015-06-03 Francesco Cerutti , Nathan Hartland

A thorough understanding of the issues surrounding the determination of parton distributions is crucial due to their importance to calculations of LHC observables. However, it is still not fully understood how much of an impact…

High Energy Physics - Phenomenology · Physics 2014-09-16 Christopher S. Deans

The parton distribution functions (PDFs) of the proton, a necessary input to almost all theory predictions for hadron colliders, are reviewed in this document. An introduction to the PDF determination by global analyses of the main PDF…

High Energy Physics - Phenomenology · Physics 2019-08-14 Ringaile Placakyte

We present an updated determination of nuclear parton distributions (nPDFs) from a global NLO QCD analysis of hard processes in fixed-target lepton-nucleus and proton-nucleus together with collider proton-nucleus experiments. In addition to…

High Energy Physics - Phenomenology · Physics 2022-05-27 Rabah Abdul Khalek , Rhorry Gauld , Tommaso Giani , Emanuele R. Nocera , Tanjona R. Rabemananjara , Juan Rojo

I consider variations in the definition of a General-Mass Variable Flavour Number Scheme (GM-VFNS) for heavy flavour structure functions, both at next-to-leading order (NLO) and at next-to-next-to leading order (NNLO). I also define a new…

High Energy Physics - Phenomenology · Physics 2010-11-19 R. S. Thorne

Study of parton distribution functions (PDFs) has led to a finer cognisance of the structure of partons in hadrons and the proton structure functions in deep inelastic scattering (DIS). PDFs are instrumental in predicting results for most…

High Energy Physics - Phenomenology · Physics 2025-10-02 Akbari Jahan , Diptimonta Neog

The electron, positron, and photon Parton Distribution Functions (PDFs) of the unpolarised electron have recently been computed at the next-to-leading logarithmic accuracy in QED, by adopting the $\overline{\rm MS}$ factorisation scheme. We…

High Energy Physics - Phenomenology · Physics 2021-12-22 Stefano Frixione

This paper investigates the crucial role of parton distribution functions (PDFs) in high-energy physics, particularly their impact on the extraction of generalized parton distributions (GPDs) at zero skewness. To this aim, we perform six…

High Energy Physics - Phenomenology · Physics 2026-03-23 The MMGPDs Collaboration , Fatemeh Irani , Muhammad Goharipour , K. Azizi

Global perturbative QCD analyses, based on large data sets from e-p and hadron collider experiments, provide tight constraints on the parton distribution function (PDF) in the proton. The extension of these analyses to nuclear parton…

High Energy Physics - Phenomenology · Physics 2011-04-07 Paloma Quiroga-Arias , José Guilherme Milhano , Urs Achim Wiedemann

In this article we obtain a new set of nuclear parton distribution functions (nuclear PDFs) at next-to-leading order and next-to-next-to-leading order accuracy in perturbative QCD. The common nuclear deep-inelastic scattering (DIS) data…

High Energy Physics - Phenomenology · Physics 2021-08-17 Hamzeh Khanpour , Maryam Soleymaninia , S. Atashbar Tehrani , Hubert Spiesberger , Vadim Guzey

Novel PDFs taking into account resummation-improved matrix elements, albeit only in the fit of a reduced data set, allow for consistent NLO+NLL calculations of slepton pair production at the LHC. We apply a factorisation method to this…

High Energy Physics - Phenomenology · Physics 2018-04-18 J. Fiaschi , M. Klasen

The precise knowledge of parton distribution functions (PDFs) is indispensable to the accurate calculation of hadron-initiated QCD hard scattering observables. Much of our information on PDFs is extracted by comparing deep inelastic…

High Energy Physics - Phenomenology · Physics 2013-10-03 David Westmark

We discuss a test of the generalization power of the methodology used in the determination of parton distribution functions (PDFs). The "future test" checks whether the uncertainty on PDFs, in regions in which they are not constrained by…

High Energy Physics - Phenomenology · Physics 2021-04-21 Juan Cruz-Martinez , Stefano Forte , Emanuele R. Nocera

The computation of the parton distribution functions (PDF) or distribution amplitudes (DA) of hadrons from first principles lattice QCD constitutes a central open problem. In this study, we present and evaluate the efficiency of a selection…

High Energy Physics - Lattice · Physics 2019-05-01 Joseph Karpie , Kostas Orginos , Alexander Rothkopf , Savvas Zafeiropoulos

We introduce a generalized definition of parton distribution functions (PDFs) for a more consistent all-order treatment of power corrections. We present a new set of modified DGLAP evolution equations for nuclear PDFs, and show that the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Zhong-Bo Kang , Jian-Wei Qiu

We compare the cross section for exclusive $J/\psi$ photoproduction calculated at NLO in the collinear factorization approach with HERA and LHCb data. Using the optimum scale formalism together with the subtraction of the low $k_t<Q_0$…

High Energy Physics - Phenomenology · Physics 2020-05-20 Chris A. Flett , Stephen P. Jones , Alan D. Martin , Misha G. Ryskin , Thomas Teubner

I explain the current status of parton-distribution-function (PDF) studies and future experimental prospects on their determinations. First, unpolarized PDFs of the nucleon are introduced as a field of precision QCD physics including…

High Energy Physics - Phenomenology · Physics 2018-09-17 S. Kumano

We investigate the uncertainty in the value of the strong coupling $\alpha_S(M_Z^2)$ when allowing it to be a free parameter in the recent MMHT global analyses of deep-inelastic and related hard scattering data that was undertaken to…

High Energy Physics - Phenomenology · Physics 2015-10-28 L. A. Harland-Lang , A. D. Martin , P. Motylinski , R. S. Thorne

We discuss the physical nature of quasi-PDFs, especially the reasons for the strong nonperturbative evolution pattern which they reveal in actual lattice gauge calculations. We argue that quasi-PDFs may be treated as hybrids of PDFs and the…

High Energy Physics - Phenomenology · Physics 2017-11-17 Anatoly Radyushkin