The Path to N$^3$LO Parton Distributions

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Main Authors: The NNPDF Collaboration, Ball, Richard D., Barontini, Andrea, Candido, Alessandro, Carrazza, Stefano, Cruz-Martinez, Juan, Del Debbio, Luigi, Forte, Stefano, Giani, Tommaso, Hekhorn, Felix, Kassabov, Zahari, Laurenti, Niccolò, Magni, Giacomo, Nocera, Emanuele R., Rabemananjara, Tanjona R., Rojo, Juan, Schwan, Christopher, Stegeman, Roy, Ubiali, Maria
Format: Preprint
Published: 2024
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author The NNPDF Collaboration
Ball, Richard D.
Barontini, Andrea
Candido, Alessandro
Carrazza, Stefano
Cruz-Martinez, Juan
Del Debbio, Luigi
Forte, Stefano
Giani, Tommaso
Hekhorn, Felix
Kassabov, Zahari
Laurenti, Niccolò
Magni, Giacomo
Nocera, Emanuele R.
Rabemananjara, Tanjona R.
Rojo, Juan
Schwan, Christopher
Stegeman, Roy
Ubiali, Maria
author_facet The NNPDF Collaboration
Ball, Richard D.
Barontini, Andrea
Candido, Alessandro
Carrazza, Stefano
Cruz-Martinez, Juan
Del Debbio, Luigi
Forte, Stefano
Giani, Tommaso
Hekhorn, Felix
Kassabov, Zahari
Laurenti, Niccolò
Magni, Giacomo
Nocera, Emanuele R.
Rabemananjara, Tanjona R.
Rojo, Juan
Schwan, Christopher
Stegeman, Roy
Ubiali, Maria
contents We extend the existing leading (LO), next-to-leading (NLO), and next-to-next-to-leading order (NNLO) NNPDF4.0 sets of parton distribution functions (PDFs) to approximate next-to-next-to-next-to-leading order (aN$^3$LO). We construct an approximation to the N$^3$LO splitting functions that includes all available partial information from both fixed-order computations and from small and large $x$ resummation, and estimate the uncertainty on this approximation by varying the set of basis functions used to construct the approximation. We include known N$^3$LO corrections to deep-inelastic scattering structure functions and extend the FONLL general-mass scheme to $\mathcal{O}\left( α_s^3\right)$ accuracy. We determine a set of aN$^3$LO PDFs by accounting both for the uncertainty on splitting functions due to the incomplete knowledge of N$^3$LO terms, and to the uncertainty related to missing higher corrections (MHOU), estimated by scale variation, through a theory covariance matrix formalism. We assess the perturbative stability of the resulting PDFs, we study the impact of MHOUs on them, and we compare our results to the aN$^3$LO PDFs from the MSHT group. We examine the phenomenological impact of aN$^3$LO corrections on parton luminosities at the LHC, and give a first assessment of the impact of aN$^3$LO PDFs on the Higgs and Drell-Yan total production cross-sections. We find that the aN$^3$LO NNPDF4.0 PDFs are consistent within uncertainties with their NNLO counterparts, that they improve the description of the global dataset and the perturbative convergence of Higgs and Drell-Yan cross-sections, and that MHOUs on PDFs decrease substantially with the increase of perturbative order.
format Preprint
id arxiv_https___arxiv_org_abs_2402_18635
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Path to N$^3$LO Parton Distributions
The NNPDF Collaboration
Ball, Richard D.
Barontini, Andrea
Candido, Alessandro
Carrazza, Stefano
Cruz-Martinez, Juan
Del Debbio, Luigi
Forte, Stefano
Giani, Tommaso
Hekhorn, Felix
Kassabov, Zahari
Laurenti, Niccolò
Magni, Giacomo
Nocera, Emanuele R.
Rabemananjara, Tanjona R.
Rojo, Juan
Schwan, Christopher
Stegeman, Roy
Ubiali, Maria
High Energy Physics - Phenomenology
High Energy Physics - Experiment
We extend the existing leading (LO), next-to-leading (NLO), and next-to-next-to-leading order (NNLO) NNPDF4.0 sets of parton distribution functions (PDFs) to approximate next-to-next-to-next-to-leading order (aN$^3$LO). We construct an approximation to the N$^3$LO splitting functions that includes all available partial information from both fixed-order computations and from small and large $x$ resummation, and estimate the uncertainty on this approximation by varying the set of basis functions used to construct the approximation. We include known N$^3$LO corrections to deep-inelastic scattering structure functions and extend the FONLL general-mass scheme to $\mathcal{O}\left( α_s^3\right)$ accuracy. We determine a set of aN$^3$LO PDFs by accounting both for the uncertainty on splitting functions due to the incomplete knowledge of N$^3$LO terms, and to the uncertainty related to missing higher corrections (MHOU), estimated by scale variation, through a theory covariance matrix formalism. We assess the perturbative stability of the resulting PDFs, we study the impact of MHOUs on them, and we compare our results to the aN$^3$LO PDFs from the MSHT group. We examine the phenomenological impact of aN$^3$LO corrections on parton luminosities at the LHC, and give a first assessment of the impact of aN$^3$LO PDFs on the Higgs and Drell-Yan total production cross-sections. We find that the aN$^3$LO NNPDF4.0 PDFs are consistent within uncertainties with their NNLO counterparts, that they improve the description of the global dataset and the perturbative convergence of Higgs and Drell-Yan cross-sections, and that MHOUs on PDFs decrease substantially with the increase of perturbative order.
title The Path to N$^3$LO Parton Distributions
topic High Energy Physics - Phenomenology
High Energy Physics - Experiment
url https://arxiv.org/abs/2402.18635