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The formulas directly connecting parton distribution functions (PDFs) at the leading (LO) and the next to leading (NLO) QCD orders are applied to both unpolarized and polarized valence PDFs and produce improved LO results on these…

High Energy Physics - Phenomenology · Physics 2014-03-11 O. Yu. Shevchenko , R. R. Akhunzyanov

We propose a new method to calculate parton distribution functions (PDFs) from lattice correlations of boosted quarks and gluons in the Coulomb gauge. Compared to the widely used gauge-invariant Wilson-line operators, these correlations…

High Energy Physics - Phenomenology · Physics 2024-04-30 Xiang Gao , Wei-Yang Liu , Yong Zhao

We present all-order results for the highest three large-x logarithms of the splitting functions P_qg and P_gq and of the coefficient functions C_phi,q, C_2,g and C_L,g for structure functions in Higgs- and gauge-boson exchange DIS in…

High Energy Physics - Phenomenology · Physics 2011-03-18 A. A. Almasy , G. Soar , A. Vogt

We use the nCTEQ analysis framework to investigate nuclear Parton Distribution Functions (nPDFs) in the region of large x and intermediate-to-low $Q$, with special attention to recent JLab Deep Inelastic Scattering data on nuclear targets.…

We investigate the basic features of the gluon density predicted by a renormalisation group improved small-x equation which incorporates both the gluon splitting function at leading collinear level and the exact BFKL kernel at…

High Energy Physics - Phenomenology · Physics 2010-03-25 M. Ciafaloni , D. Colferai , G. P. Salam , A. M. Stasto

We present state of the art resummation predictions for differential cross sections in top-quark pair production at the LHC. They are derived from a formalism which allows the simultaneous resummation of both soft and small-mass logarithms,…

High Energy Physics - Phenomenology · Physics 2016-05-25 Benjamin D. Pecjak , Darren J. Scott , Xing Wang , Li Lin Yang

We discuss different resummations of large logarithms that arise in hard-scattering cross sections of quarks and gluons in regions of large and small x. The large-x logarithms are typically dominant near threshold for the production of a…

High Energy Physics - Phenomenology · Physics 2010-03-30 Nikolaos Kidonakis , Agustin Sabio Vera , Philip Stephens

We derived the conditions on certain combinations of integrals of the fragmentation functions of pion using HERMES data of the sum for the charged pion multiplicities from semi-inclusive deep-inelastic scattering (SIDIS) off the deuteron…

High Energy Physics - Phenomenology · Physics 2016-03-23 Dong-Jing Yang , Fu-Jiun Jiang , Wen-Chen Chang , Chung-Wen Kao , Seung-il Nam

We present a determination of the parton distributions of the nucleon from a global set of hard scattering data using the NNPDF methodology: NNPDF2.0. Experimental data include deep-inelastic scattering with the combined HERA-I dataset,…

High Energy Physics - Phenomenology · Physics 2014-11-20 Richard D. Ball , Luigi Del Debbio , Stefano Forte , Alberto Guffanti , Jose I. Latorre , Juan Rojo , Maria Ubiali

We show that the parton distribution functions (PDF) described by the statistical model have very interesting physical properties which help to understand the structure of partons. The role of the quark helicity components is emphasized as…

High Energy Physics - Phenomenology · Physics 2015-09-28 Claude Bourrely

Modern global analyses of the structure of the proton include collider measurements which probe energies well above the electroweak scale. While these provide powerful constraints on the parton distribution functions (PDFs), they are also…

High Energy Physics - Phenomenology · Physics 2019-10-02 Stefano Carrazza , Celine Degrande , Shayan Iranipour , Juan Rojo , Maria Ubiali

The full exploitation of the increasingly precise LHC measurements is essential in order to reduce the uncertainty of theoretical predictions at hadron colliders. The NNPDF2.3 fit was the first PDF determination including the effect of the…

High Energy Physics - Phenomenology · Physics 2014-07-14 Maria Ubiali

The nuclear parton distribution functions (nPDFs) of gluons are known to be difficult to determine with fits of deep inelastic scattering (DIS) and Drell-Yan (DY) data alone. Therefore, the nCTEQ15 analysis of nuclear PDFs added inclusive…

High Energy Physics - Phenomenology · Physics 2021-08-02 P. Duwentäster , L. A. Husová , T. Ježo , M. Klasen , K. Kovařík , A. Kusina , K. F. Muzakka , F. I. Olness , I. Schienbein , J. Y. Yu

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

High Energy Physics - Phenomenology · Physics 2012-11-12 R. S. Thorne

We investigate the evolution of parton densities at small values of the momentum fraction, x, by including resummed anomalous dimensions in the renormalization group equations. The resummation takes into account the leading-logarithmic…

High Energy Physics - Phenomenology · Physics 2016-09-01 R. K. Ellis , F. Hautmann , B. R. Webber

Nuclear parton distribution functions (nuclear PDFs) are non-perturbative objects that encode the partonic behaviour of bound nucleons. To avoid potential higher-twist contributions, the data probing the high-$x$ end of nuclear PDFs are…

High Energy Physics - Phenomenology · Physics 2020-06-24 Hannu Paukkunen , Pia Zurita

We report current status of global analyses on nuclear parton distribution functions (NPDFs). The optimum NPDFs are determined by analyzing high-energy nuclear reaction data. Due to limited experimental measurements, antiquark modifications…

High Energy Physics - Phenomenology · Physics 2015-05-27 M. Hirai , S. Kumano , K. Saito

We construct predictions for top quark pair differential distributions at hadron colliders that combine state-of-the-art NNLO QCD calculations with double resummation at NNLL' accuracy of threshold logarithms arising from soft gluon…

High Energy Physics - Phenomenology · Physics 2018-06-07 Michal Czakon , Andrea Ferroglia , David Heymes , Alexander Mitov , Ben D. Pecjak , Darren J. Scott , Xing Wang , Li Lin Yang

Hessian PDF reweighting, or "profiling", has become a widely used way to study the impact of a new data set on parton distribution functions (PDFs) with Hessian error sets. The available implementations of this method have resorted to a…

High Energy Physics - Phenomenology · Physics 2019-09-27 Kari J. Eskola , Petja Paakkinen , Hannu Paukkunen

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