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arxiv 2503.11814 v2 pith:HF7ID2NO submitted 2025-03-14 hep-ph hep-exnucl-exnucl-th

NNPDFpol2.0: a global determination of polarised PDFs and their uncertainties at next-to-next-to-leading order

classification hep-ph hep-exnucl-exnucl-th
keywords pdfsnnpdfpol2polarisedcorrectionsdeterminationlongitudinallyuncertaintiescollisions
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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We present NNPDFpol2.0, a new set of collinear helicity parton distribution functions (PDFs) of the proton based on legacy measurements of structure functions in inclusive neutral-current longitudinally polarised deep-inelastic scattering (DIS), and of W -boson, single-inclusive, and di-jet production asymmetries in longitudinally polarised proton-proton collisions. The determination is accurate to next-to-next-to-leading order in the strong coupling, and includes heavy quark mass corrections in the analysis of DIS data. Uncertainties due to missing higher-order corrections are systematically incorporated by means of a covariance matrix determined by scale variations. NNPDFpol2.0 is based on a machine learning methodology, that makes use of Monte Carlo sampling for the representation of uncertainties into PDFs, of a neural network for the parametrisation of PDFs, of stochastic gradient descent for the optimisation of PDF parameters, and of hyperoptimisation for the selection of the best fitting model. We study the impact on PDFs of higher-order corrections, of the positivity constraint, and of the data. We demonstrate two phenomenological applications of NNPDFpol2.0, specifically the determination of the proton spin fraction carried by gluons and quarks, and of theoretical predictions for single-hadron production in longitudinally polarised DIS and proton-proton collisions.

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Forward citations

Cited by 6 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

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    hep-ph 2025-07 unverdicted novelty 7.0

    Non-singlet fragmentation functions of pions and kaons are determined at NNLO QCD from charge asymmetry measurements in e+e- annihilation and SIDIS, yielding a scaling index of 0.7 and strangeness suppression of 0.5.

  2. Polarized Deep-Inelastic Scattering with Spin Correlations in Herwig 7

    hep-ph 2026-06 unverdicted novelty 5.0

    Herwig 7 now supports NLO POWHEG-matched polarized DIS including neutral and charged currents, with spin-density matrix propagation that affects some shower observables but not others.

  3. Probing Nucleon Spin Structure with a Polarized Gamma Beam from Compton Backscattering at FCC-ee

    hep-ex 2026-06 unverdicted novelty 5.0

    Proposes a Compton backscattering gamma facility at FCC-ee and projects 1.8-3.0% precision on Δg/g in the medium-x region via open-charm photoproduction on a polarized NH3 target.

  4. Energy Correlators Resolving Proton Spin

    hep-ph 2025-09 unverdicted novelty 5.0

    The work establishes a correspondence between spin-dependent energy correlators and polarized TMDs/NECs using SCET, yielding N3LL/N2LL predictions for correlation patterns in current and target fragmentation regions.

  5. PineAPPLv1: fast and flexible theory predictions for present and future colliders

    hep-ph 2026-06 unverdicted novelty 4.0

    PineAPPLv1 provides interpolation tables supporting multiple convolutions with polarised and unpolarised PDFs and FFs for fast collider observable predictions.

  6. Proton-Proton to Antinucleon Cross Sections for Cosmic Ray Applications

    hep-ph 2026-05 unverdicted novelty 4.0

    NLO perturbative QCD calculations predict only a mild few-percent excess of antineutrons over antiprotons in pp collisions, not supporting the ~30% excess reported by NA49.