The photon content of the proton

By A. Manohar, P. Nason, G. Salam, G. Zanderighi. Journal of High Energy Physics, 2017

254 citations recorded by the source corpus.

The photon PDF of the proton is needed for precision comparisons of LHC cross sections with theoretical predictions. In a recent paper, we showed how the photon PDF could be determined in terms of the electromagnetic proton structure functions F2 and FL measured in electron-proton scattering experiments, and gave an explicit formula for the PDF including all terms up to next-to-leading order. In this paper we give details of the derivation. We obtain the photon PDF using the factorisation theorem and applying it to suitable BSM hard scattering processes. We also obtain the same PDF in a process-independent manner using the usual definition of PDFs in terms of light-cone Fourier transforms of products of operators. We show how our method gives an exact representation for the photon PDF in terms of F2 and FL, valid to all orders in QED and QCD, and including all non-perturbative corrections. This representation is then used to give an explicit formula for the photon PDF to one order higher than our previous result. We also generalise our results to obtain formulæ for the polarised photon PDF, as well as the photon TMDPDF. Using our formula, we derive the Pγi subset of DGLAP splitting functions to order ααs and α2, which agree with known results. We give a detailed explanation of the approach that we follow to determine a photon PDF and its uncertainty within the above framework.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/fcbf6888d29ad4f9ea05291345dd46f8543e9773

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Citations in the corpus

Large NLO corrections in tt¯ W ± and tt¯ tt¯ hadroproduction from supposedly subleading EW contributions (2018, methodology): “Concerning the PDFs, we use the LUXqed plus PDF4LHC15 nnlo 100 set [57, 58], which is in turn based on the PDF4LHC set [59–62].”
Higgs Physics at the HL-LHC and HE-LHC (2019, methodology): “We also notice that the relative weight of the photon-induced channel is computed more reliably than in the results previously obtained for the YR4 study: the changes in the values of from the YR4 results (which also had large uncertainties) to those presented here are indeed non-negligible, and the”
Illuminating the photon content of the proton within a global PDF analysis (2017, methodology): “The following sources of uncertainty are considered [42]: the elastic contribution from the A1 world proton form factor fits [103]; the parametrisation of the DIS structure functions in the resonance region [104–106]; the parametrisation of RL/T [107, 118, 119], the ratio between longitudinal and tr”
Lepton Number Violation: Seesaw Models and Their Collider Tests (2017, background): “1+LUXqed (lhaid=324900) [270], LUXqed17+PDF4LHC15 (lhaid=82200) [271, 272], and CT14 QED Inclusive (lhaid = 13300) [273].”