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Illuminating the photon content of the proton within a global PDF analysis

by Valerio Bertone, Stefano Carrazza, Nathan P. Hartland, Juan Rojo

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Submission summary

Authors (as registered SciPost users): Stefano Carrazza
Submission information
Preprint Link:  (pdf)
Date accepted: 2018-05-29
Date submitted: 2018-05-25 02:00
Submitted by: Carrazza, Stefano
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • High-Energy Physics - Experiment
  • High-Energy Physics - Phenomenology
  • Nuclear Physics - Theory
Approach: Theoretical


Precision phenomenology at the LHC requires accounting for both higher-order QCD and electroweak corrections as well as for photon-initiated subprocesses. Building upon the recent NNPDF3.1 fit, in this work the photon content of the proton is determined within a global analysis supplemented by the LUXqed constraint relating the photon PDF to lepton-proton scattering structure functions: NNPDF3.1luxQED. The uncertainties on the resulting photon PDF are at the level of a few percent, with photons carrying up to 0.5% of the proton's momentum. We study the phenomenological implications of NNPDF3.1luxQED at the LHC for Drell-Yan, vector boson pair, top quark pair, and Higgs plus vector boson production. We find that photon-initiated contributions can be significant for many processes, leading to corrections of up to 20%. Our results represent a state-of-the-art determination of the partonic structure of the proton including its photon component.

Author comments upon resubmission

Updated version incorporating last changes requested by referee.

List of changes

As listed in the last referee reply.

Published as SciPost Phys. 5, 008 (2018)

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