Photons in the proton: implications for the LHC
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jats:titleAbstract</jats:title>jats:pWe construct a set of parton distribution functions (PDFs), based on the recent NNPDF4.0 PDF set, that also include a photon PDF. The photon PDF is constructed using the LuxQED formalism, while QED evolution accounting for jats:inline-formulajats:alternativesjats:tex-math$${\mathcal {O}}\left( \alpha \right) $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> mml:mrow mml:miO</mml:mi> mml:mfenced mml:miα</mml:mi> </mml:mfenced> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula>, jats:inline-formulajats:alternativesjats:tex-math$${\mathcal {O}}\left( \alpha \alpha _s\right) $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> mml:mrow mml:miO</mml:mi> mml:mfenced mml:miα</mml:mi> mml:msub mml:miα</mml:mi> mml:mis</mml:mi> </mml:msub> </mml:mfenced> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula>, and jats:inline-formulajats:alternativesjats:tex-math$${\mathcal {O}}\left( \alpha ^2\right) $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> mml:mrow mml:miO</mml:mi> mml:mfenced mml:msup mml:miα</mml:mi> mml:mn2</mml:mn> </mml:msup> </mml:mfenced> </mml:mrow> </mml:math></jats:alternatives></jats:inline-formula> corrections is implemented and benchmarked by means of the jats:scEKO</jats:sc> code. We investigate the impact of QED effects on NNPDF4.0, and compare our results both to our previous NNPDF3.1QED PDF set and to other recent PDF sets that include the photon. We assess the impact of photon-initiated processes and electroweak corrections on a variety of representative LHC processes, and find that they can reach the 5% level in vector boson pair production at large invariant mass.</jats:p>
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Acknowledgements: We thank Valerio Bertone for assistance with the benchmarking of QED evolution with APFEL, and Lucian Harland-Lang and Luca Buonocore for discussions on the LuxQED procedure. R. D. B, L. D. D., and R. S. are supported by the U.K. Science and Technology Facility Council (STFC) grant ST/T000600/1. F. H. is supported by the Academy of Finland project 358090 and is funded as a part of the Center of Excellence in Quark Matter of the Academy of Finland, project 346326. E. R. N. is supported by the Italian Ministry of University and Research (MUR) through the “Rita Levi-Montalcini” Program. M. U. and Z. K. are supported by the European Research Council under the European Union’s Horizon 2020 research and innovation Programme (grant agreement n.950246), and partially by the STFC consolidated grant ST/L000385/1. J. R. is partially supported by NWO, the Dutch Research Council. C. S. is supported by the German Research Foundation (DFG) under reference number DE 623/6-2.
Funder: Nederlandse Organisatie voor Wetenschappelijk Onderzoek; doi: http://dx.doi.org/10.13039/501100003246
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1434-6052
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Science and Technology Facilities Council (ST/L000385/1, ST/T000600/1)
Deutsche Forschungsgemeinschaft (DE 623/6-2)
Ministero dell’Università e della Ricerca (Rita Levi-Montalcini)