McGowan, J;
Cridge, T;
Harland-Lang, LA;
Thorne, RS;
(2023)
Approximate N3
LO parton distribution functions with theoretical uncertainties: MSHT20aN3
LO PDFs.
The European Physical Journal C
, 83
(3)
, Article 185. 10.1140/epjc/s10052-023-11236-0.
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Abstract
We present the first global analysis of parton distribution functions (PDFs) at approximate N3LO in the strong coupling constant αs, extending beyond the current highest NNLO achieved in PDF fits. To achieve this, we present a general formalism for the inclusion of theoretical uncertainties associated with the perturbative expansion in the strong coupling. We demonstrate how using the currently available knowledge surrounding the next highest order (N3LO) in αs can provide consistent, justifiable and explainable approximate N3LO (aN3LO) PDFs. This includes estimates for uncertainties due the currently unknown N3LO ingredients, but also implicitly some missing higher order uncertainties (MHOUs) beyond these. Specifically, we approximate the splitting functions, transition matrix elements, coefficient functions and K-factors for multiple processes to N3LO. Crucially, these are constrained to be consistent with the wide range of already available information about N3LO to match the complete result at this order as accurately as possible. Using this approach we perform a fully consistent approximate N3LO global fit within the MSHT framework. This relies on an expansion of the Hessian procedure used in previous MSHT fits to allow for sources of theoretical uncertainties. These are included as nuisance parameters in a global fit, controlled by knowledge and intuition based prior distributions. We analyse the differences between our aN3LO PDFs and the standard NNLO PDF set, and study the impact of using aN3LO PDFs on the LHC production of a Higgs boson at this order. Finally, we provide guidelines on how these PDFs should be used in phenomenological investigations.
| Type: | Article |
|---|---|
| Title: | Approximate N3 LO parton distribution functions with theoretical uncertainties: MSHT20aN3 LO PDFs |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1140/epjc/s10052-023-11236-0 |
| Publisher version: | https://doi.org/10.1140/epjc/s10052-023-11236-0 |
| Language: | English |
| Additional information: | This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit (http://creativecommons.org/licenses/by/4.0/). |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10167646 |
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