Unbiased global determination of parton distributions and their uncertainties at NNLO and at LO

By T. Ball, Valerio Bertone, F. Cerutti, Luigi Del Debbio, S. Forte, Alberto Guffanti, Jose I.Latorre, Juan Rojo, M. Ubiali. 2011

316 citations recorded by the source corpus.

We present a determination of the parton distributions of the nucleon from a global set of hard scattering data using the NNPDF methodology at LO and NNLO in perturbative QCD, thereby generalizing to these orders the NNPDF2.1 NLO parton set. Heavy quark masses are included using the so-called FONLL method, which is benchmarked here at NNLO. We demonstrate the stability of PDFs upon inclusion of NNLO corrections, and we investigate the convergence of the perturbative expansion by comparing LO, NLO and NNLO results. We show that the momentum sum rule can be tested with increasing accuracy at LO, NLO and NNLO. We discuss the impact of NNLO corrections on collider phenomenology, specifically by comparing to recent LHC data. We present PDF determinations using a range of values of αs, mc and mb. We also present PDF determinations based on various subsets of the global dataset, show that they generally lead to less accurate phenomenology, and discuss the possibility of future PDF determinations based on collider data only.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/959390955570e114e1b0421aa809dd9fd6d195f7

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In Nuclear and High Energy Physics

Citations in the corpus

Measurements of properties of the Higgs boson decaying into the four-lepton final state in pp collisions at s=13$$ \sqrt{s}=13 $$ TeV (2017, methodology): “The default set of parton distribution functions (PDFs) used in all simulations is NNPDF30 nlo as 0118 [36].”
The Structure of the Proton in the LHC Precision Era (2017, methodology): “1 [133, 134] provided the first NNLO PDF set within this approach, and included Tevatron data for the first time.”
Parton distributions for the LHC run II (2014, methodology): “[12]: we define C-factors as the ratio of NNLO to NLO calculations for fixed NNLO PDFs, that is C ≡ σ̂ nnlo ⊗ Lnnlo σ̂nlo ⊗ Lnnlo , (1) where σ̂ is the partonic cross section computed at either NNLO or NLO accuracy, and Lnnlo is the corresponding parton luminosity computed with a reference set of NN”
PDF4LHC recommendations for LHC Run II (2015, unknown): “These PDFs were later also made available at NNLO [41].”
A critical appraisal and evaluation of modern PDFs (2016, background): “[183] NNPDF Collaboration, R.”
Event generator tunes obtained from underlying event and multiparton scattering measurements (2015, unknown): “3LO [22, 23]), (ii) new PYTHIA6 (version 6.”