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We present a global fit of parton distributions at next-to-next-to-leading order (NNLO) in QCD. The fit is based on the world data for deep-inelastic scattering, fixed-target data for the Drell-Yan process and includes, for the first time,…

High Energy Physics - Phenomenology · Physics 2014-04-02 S. Alekhin , J. Bluemlein , S. Moch

We will show an application of neural networks to extract information on the structure of hadrons. A Monte Carlo over experimental data is performed to correctly reproduce data errors and correlations. A neural network is then trained on…

High Energy Physics - Phenomenology · Physics 2019-08-14 Andrea Piccione , Joan Rojo

We briefly discuss recent results on the evolution of unpolarized parton densities and structure functions in massless perturbative QCD. Present partial results on the next-to-next-to-leading order (NNLO) evolution kernels prove sufficient…

High Energy Physics - Phenomenology · Physics 2009-10-31 W. L. van Neerven , A. Vogt

We discuss a modification of the next-to-next-to-leading order (NNLO) subtraction scheme based on the residue-improved sector decomposition that reduces the number of double-real emission sectors from five to four. In particular, a sector…

High Energy Physics - Phenomenology · Physics 2017-05-24 Fabrizio Caola , Kirill Melnikov , Raoul Röntsch

We present a combined next-to-leading order QCD analysis to data on both inclusive and semi-inclusive polarized deep inelastic scattering asymmetries. Performing NLO QCD global fits with different sets of observables, we evaluate the impact…

High Energy Physics - Phenomenology · Physics 2009-10-30 D. de Florian , O. Sampayo , R. Sassot

We discuss the theoretical bases that underpin the automation of the computations of tree-level and next-to-leading order cross sections, of their matching to parton shower simulations, and of the merging of matched samples that differ by…

High Energy Physics - Phenomenology · Physics 2015-06-19 J. Alwall , R. Frederix , S. Frixione , V. Hirschi , F. Maltoni , O. Mattelaer , H. -S. Shao , T. Stelzer , P. Torrielli , M. Zaro

A next-to-leading order QCD analysis of spin asymmetries and structure functions in polarized deep inelastic lepton nucleon scattering is presented within the framework of the radiative parton model. A consistent NLO formulation of the…

High Energy Physics - Phenomenology · Physics 2009-10-28 M. Gluck , E. Reya , M. Stratmann , W. Vogelsang

We present an analytical solution for the evolution of parton distributions incorporating mixed-order QCD $\otimes$ QED corrections, addressing both polarized and unpolarized cases. Using the Altarelli-Parisi kernels extended to mixed…

High Energy Physics - Phenomenology · Physics 2026-02-16 Daniel de Florian , Lucas Palma Conte

Recent developments in QCD phenomenology have spurred on several improved approaches to Monte Carlo event generation, relative to the post--LEP state of the art. In this brief review, the emphasis is placed on approaches for 1) consistently…

High Energy Physics - Phenomenology · Physics 2009-11-11 Peter Z. Skands

Monte Carlo event generators for hard hadronic collisions depend on the evolution of parton showers backwards from a high-scale subprocess to the hadronization scale. The evolution is treated as a branching process with a sequence of…

High Energy Physics - Phenomenology · Physics 2024-04-16 Stefano Frixione , Bryan R. Webber

We present a calculation of the next-to-leading order (NLO) QCD corrections to gluon-induced electroweak gauge boson pair production, $gg \to ZZ$ and $gg \to W^+W^-$, matched to the PYTHIA8 parton shower in the POWHEG approach. The…

High Energy Physics - Phenomenology · Physics 2021-08-18 Simone Alioli , Silvia Ferrario Ravasio , Jonas M. Lindert , Raoul Röntsch

We investigate numerical solution of the Dokshitzer-Gribov-Lipatov-Altarelli- Parisi (DGLAP) Q^2 evolution equation for the transversity distribution Delta_T q or the structure function h_1. The leading-order (LO) and next-to- leading-order…

High Energy Physics - Phenomenology · Physics 2014-11-17 M. Hirai , S. Kumano , M. Miyama

We develop a novel Monte Carlo parton branching algorithm based on the Gribov-Levin-Ryskin (GLR) equation. The formulations of both forward evolution and backward evolution for the GLR equation are presented. The results from the Monte…

High Energy Physics - Phenomenology · Physics 2023-02-08 Yu Shi , Shu-Yi Wei , Jian Zhou

In this work, using the Laplace transformation technique we present our results for non-singlet quark distributions as well as nucleon structure function $F_2(x,Q^2)$ in unpolarized case at next-to-next-to-leading order (NNLO) QCD accuracy.…

High Energy Physics - Phenomenology · Physics 2020-06-09 Maral Salajegheh , S. Mohammad Moosavi Nejad , Abolfazl Mirjalili , S. Atashbar Tehrani

We present a determination of parton distribution functions (ABM11) and the strong coupling constant alpha_s at next-to-leading order and next-to-next-to-leading order (NNLO) in QCD based on world data for deep-inelastic scattering and…

High Energy Physics - Phenomenology · Physics 2015-06-04 S. Alekhin , J. Blumlein , S. Moch

We present a generalization of the $x$-space $\texttt{Candia}$ algorithm to next-to-next-to-next-to-leading order (N$^3$LO) accuracy in Quantum Chromodynamics (QCD) for solving the DGLAP evolution equations for unpolarized parton densities…

High Energy Physics - Phenomenology · Physics 2026-03-24 Casey Hampson , Marco Guzzi

We formulate a collinear partonic shower algorithm that achieves next-to-single-logarithmic (NSL, $\alpha_s^n L^{n-1}$) accuracy for collinear-sensitive non-singlet fragmentation observables. This entails the development of an algorithm for…

High Energy Physics - Phenomenology · Physics 2024-09-16 Melissa van Beekveld , Mrinal Dasgupta , Basem Kamal El-Menoufi , Jack Helliwell , Pier Francesco Monni , Gavin P. Salam

The freedom associated with the definition of parton distribution functions is analyzed and formulae governing the dependence of parton distribution functions and hard scattering cross-sections on unphysical quantities associated with the…

High Energy Physics - Phenomenology · Physics 2011-12-20 Karel Kolar

We provide a determination of the isotriplet quark distribution from available deep--inelastic data using neural networks. We give a general introduction to the neural network approach to parton distributions, which provides a solution to…

High Energy Physics - Phenomenology · Physics 2010-10-27 The NNPDF Collaboration , Luigi Del Debbio , Stefano Forte , Jose I. Latorre , Andrea Piccione , Joan Rojo

Deeply-virtual Compton scattering gives access to the generalized parton distributions that encode the information on the transverse position of quarks and gluons in the proton in dependence in their longitudinal momentum. In anticipation…

High Energy Physics - Phenomenology · Physics 2022-11-14 V. M. Braun , Yao Ji , Jakob Schoenleber