Direct photon production and PDF fits reloaded

Abstract

Direct photon production in hadronic collisions provides a handle on the gluon PDF by means of the QCD Compton scattering process. In this work we revisit the impact of direct photon production on a global PDF analysis, motivated by the recent availability of the next-to-next-to-leading (NNLO) calculation for this process. We demonstrate that the inclusion of NNLO QCD and leading-logarithmic electroweak corrections leads to a good quantitative agreement with the ATLAS measurements at 8 TeV and 13 TeV, except for the most forward rapidity region in the former case. By including the ATLAS 8 TeV direct photon production data in the NNPDF3.1 NNLO global analysis, we assess its impact on the medium-x gluon. We also study the constraining power of the direct photon production measurements on PDF fits based on different datasets, in particular on the NNPDF3.1 no-LHC and collider-only fits. We also present updated NNLO theoretical predictions for direct photon production at 13 TeV that include the constraints from the 8 TeV measurements.

27 pages, 14 figures. Version accepted for publication in EPJC

References in corpus (4)

• LHAPDF6: parton density access in the LHC precision era
• Parton distributions in the LHC era: MMHT 2014 PDFs
• Quantitative constraints on the gluon distribution function in the proton from collider isolated-photon data
• Sensitivity of isolated photon production at TeV hadron colliders to the gluon distribution in the proton

Cited by in corpus (28)

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• The PDF4LHC21 combination of global PDF fits for the LHC Run III
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• Parton Distributions in Nucleons and Nuclei
• Nuclear Parton Distributions from Lepton-Nucleus Scattering and the Impact of an Electron-Ion Collider
• nNNPDF2.0: Quark Flavor Separation in Nuclei from LHC Data
• Towards Ultimate Parton Distributions at the High-Luminosity LHC
• Complete predictions for high-energy neutrino propagation in matter
• Next-to-leading power corrections to $V+1$ jet production in $N$-jettiness subtraction
• Constraining unintegrated gluon distributions from inclusive photon production in proton-proton collisions at the LHC
• Measurement of differential cross sections for inclusive isolated-photon and photon+jet production in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Scale and isolation sensitivity of diphoton distributions at the LHC
• Measurement of the inclusive isolated-photon cross section in $pp$ collisions at $\sqrt{s}=13$ TeV using 36 fb${}^{-1}$ of ATLAS data
• Isolated photon and photon+jet production at NNLO QCD accuracy
• Measurement of the ratio of cross sections for inclusive isolated-photon production in $pp$ collisions at $\sqrt{s}=13$ and $8$ TeV with the ATLAS detector
• The color dipole picture for prompt photon production in $pp$ and $pPb$ collisions at the CERN-LHC
• Inclusive-photon production and its dependence on photon isolation in $pp$ collisions at $\sqrt{s}=13$ TeV using 139 fb${}^{-1}$ of ATLAS data
• Vector Bosons and Jets in Proton Collisions
• Single Photon Production at Hadron Colliders at NNLO QCD with Realistic Photon Isolation
• Probing nuclear modifications of parton distribution functions through the isolated prompt photon production at the LHC
• Reconstructing partonic kinematics at colliders with Machine Learning
• Measurements of triple-differential cross sections for inclusive isolated-photon+jet events in pp collisions at $\sqrt{s}=$ 8 TeV
• An energy independent scaling of transverse momentum spectra of direct (prompt) photons from two-body processes in high-energy proton-proton collisions
• Constraining fragmentation functions through hadron-photon production at higher-orders
• Classical information entropy of parton distribution functions and an application in searching gluon saturation
• Determination of the parton distribution functions of the proton using diverse ATLAS data from $pp$ collisions at $\sqrt{s}=7$, 8 and 13 TeV
• Phenomenological extraction of fragmentation functions in a $p\bar{p}$ environment