Measurement of prompt photon production in $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV $p$+Pb collisions with ATLAS

Abstract

The inclusive production rates of isolated, prompt photons in $p$+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165 nb${}^{-1}$ recorded in 2016. The cross-section and nuclear modification factor $R_{p\mathrm{Pb}}$ are measured as a function of photon transverse energy from 20 GeV to 550 GeV and in three nucleon-nucleon centre-of-mass pseudorapidity regions, (-2.83,-2.02), (-1.84,0.91), and (1.09,1.90). The cross-section and $R_{p\mathrm{Pb}}$ values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large amount of energy loss and provide new constraints on the parton densities in nuclei.

37 pages in total, author list starting page 21, 9 figures, no tables, final version published in Phys. Lett. B. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2018-05/

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Cited by in corpus (12)

• Direct real photons in relativistic heavy ion collisions
• NNLO nuclear parton distribution functions with electroweak-boson production data from the LHC
• Jet charge modification in dense QCD matter
• Reweighted nuclear PDFs using Heavy-Flavor Production Data at the LHC: nCTEQ15_rwHF & EPPS16_rwHF
• Comparison of inclusive and photon-tagged jet suppression in 5.02 TeV Pb+Pb collisions with ATLAS
• The production of isolated photons in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV
• Contribution to differential ${\pi }^0$ and ${\gamma }_{\mathrm{dir}}$ modification in small systems from color fluctuation effects
• Prompt photon production in high-energy $pA$ collisions at forward rapidity
• Multiplicity-dependent saturation momentum in $p$-Pb collisions at 5.02 TeV
• Study of nuclear corrections on the charged hadron fragmentation functions in a Neural Network global QCD analysis
• Hard processes in multi-TeV ion collisions
• Heavy ion physics at CMS and ATLAS: hard probes