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We apply the Lagrange Multiplier method to study the uncertainties of physical predictions due to the uncertainties of parton distribution functions (PDFs), using the cross section for W production at a hadron collider as an archetypal…

High Energy Physics - Phenomenology · Physics 2009-09-25 D. Stump , J. Pumplin , R. Brock , D. Casey , J. Huston , J. Kalk , H. L. Lai , W. K. Tung

We study several sources of theoretical uncertainty in the determination of parton distributions (PDFs) which may affect current PDF sets used for precision physics at the Large Hadron Collider, and explain discrepancies between them. We…

High Energy Physics - Phenomenology · Physics 2013-05-09 The NNPDF Collaboration , Richard D. Ball , Valerio Bertone , Luigi Del Debbio , Stefano Forte , Alberto Guffanti , Juan Rojo , Maria Ubiali

We discuss the two most recent global analyses of nuclear parton distribution functions within the nCTEQ approach. LHC data on $W/Z$-boson, single-inclusive hadron and heavy quark/quarkonium production are shown to not only significantly…

High Energy Physics - Phenomenology · Physics 2022-10-20 M. Klasen , P. Duwentäster , T. Jezo , K. Kovarik , A. Kusina , J. G. Morfin , K. F. Muzakka , F. I. Olness , R. Ruiz , I. Schienbein , J. Y. Yu

The photon parton distribution function (PDF) of the proton is crucial for precise comparisons of LHC cross sections with theoretical predictions. However, it was previously affected by very large uncertainties of around ${\cal O}(100\%)$…

High Energy Physics - Phenomenology · Physics 2024-08-26 Aneesh Manohar , Paolo Nason , Gavin Salam , Giulia Zanderighi

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

At the LHC we are colliding protons, but it is not the protons that are doing the interacting. It is their constituents the quarks, antiquarks and gluons-collectively known as partons. We need to know how what fractional momentum of the…

High Energy Physics - Phenomenology · Physics 2023-02-24 A M Cooper-Sarkar

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 study the charged current Drell-Yan process and we evaluate the proton parton densities uncertainties on the lepton transverse momentum distribution and their impact on the determination of the W-boson mass. We consider the global PDF…

High Energy Physics - Phenomenology · Physics 2015-06-17 Giuseppe Bozzi , Luca Citelli , Alessandro Vicini

The LHC has recently released precise measurements of the transverse momentum distribution of the Z-boson that provide a unique constraint on the structure of the proton. Theoretical developments now allow the prediction of these…

High Energy Physics - Phenomenology · Physics 2017-09-13 Radja Boughezal , Alberto Guffanti , Frank Petriello , Maria Ubiali

We present a new QCD analysis of parton distribution functions (PDFs) at the next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). In the present paper, the role of special types of experimental measurements for extracting…

High Energy Physics - Phenomenology · Physics 2024-05-20 Majid Azizi , Ali Khorramian , Saeid Paktinat Mehdiabadi

We present a model-independent determination of the nuclear parton distribution functions (nPDFs) using machine learning methods and Monte Carlo techniques based on the NNPDF framework. The neutral-current deep-inelastic nuclear structure…

High Energy Physics - Phenomenology · Physics 2020-10-28 Rabah Abdul Khalek , Jacob J. Ethier , Juan Rojo , Gijs van Weelden

We perform a comprehensive analysis of the strange-antistrange parton distribution function (PDF) asymmetry in the proton in the framework of chiral effective theory, including the full set of lowest order kaon loop diagrams with off-shell…

High Energy Physics - Phenomenology · Physics 2016-12-21 X. G. Wang , Chueng-Ryong Ji , W. Melnitchouk , Y. Salamu , A. W. Thomas , P. Wang

This contribution to the Italian "Workshop sui Monte Carlo, la Fisica e le Simulazioni a LHC", held at LNF, Frascati, in February, May and October 2006, summarises the status of parton density functions (PDF's) and the impact of their…

High Energy Physics - Experiment · Physics 2019-08-13 A. Tricoli

We investigate the uncertainties of the heavy-quark parton distribution functions in the variable flavor number scheme. Because the charm- and bottom-quark parton distribution functions (PDFs) are constructed predominantly from the gluon…

High Energy Physics - Phenomenology · Physics 2008-11-26 Z. Sullivan , P. M. Nadolsky

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…

We present LO, NLO and NNLO sets of parton distribution functions (PDFs) of the proton determined from global analyses of the available hard scattering data. These MMHT2014 PDFs supersede the `MSTW2008' parton sets, but are obtained within…

High Energy Physics - Phenomenology · Physics 2015-06-11 L. A. Harland-Lang , A. D. Martin , P. Motylinski , R. S. Thorne

Parton distribution functions (pdfs) are an important ingredient for LHC phenomenology. Recent progress in determining pdfs from global analyses is reviewed, and some of the most important outstanding issues are highlighted. Particular…

High Energy Physics - Phenomenology · Physics 2008-12-15 W. James Stirling

We reexamine the dominant contribution of parton distribution function (PDF) uncertainties to the W mass measurement, and determine their contribution is +-39(30) MeV when running the Large Hadron Collider at 7(13) TeV. We find that…

High Energy Physics - Phenomenology · Physics 2015-08-19 Zack Sullivan , Seth Quackenbush

W and Z bosons will be produced copiously at the LHC proton-proton collider. We study the parton distribution dependence of the total production cross sections and rapidity distributions, paying particular attention to the uncertainties…

High Energy Physics - Phenomenology · Physics 2011-03-23 A. D. Martin , R. G. Roberts , W. J. Stirling , R. S. Thorne

High-precision electroweak production measurements from the Tevatron and the LHC provide important constraints on the quark flavor separation in global PDF fits. In this contribution, we study the impact of the recent D0 W asymmetry…

High Energy Physics - Phenomenology · Physics 2016-05-27 Juan Rojo