Measurement of the inclusive isolated-photon production cross section in pp and Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

Abstract

The ALICE Collaboration at the CERN LHC has measured the inclusive production cross section of isolated photons at midrapidity as a function of the photon transverse momentum ($p_{\mathrm{T}}^{\gamma }$), in Pb$-$Pb collisions in different centrality intervals, and in pp collisions, at centre-of-momentum energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The photon transverse momentum range is between 10-14 and 40-140 GeV/$c$, depending on the collision system and on the Pb$-$Pb centrality class. The result extends to lower $p_{\mathrm{T}}^{\gamma }$ than previously published results by the ATLAS and CMS experiments at the same collision energy. The covered pseudorapidity range is $|{\eta }^{\gamma }|<0.67$. The isolation selection is based on a charged particle isolation momentum threshold $p_{\mathrm{T}}^{\mathrm{iso},\mathrm{ch}}=1.5$ GeV/$c$ within a cone of radii $R=0.2$ and $0.4$. The nuclear modification factor is calculated and found to be consistent with unity in all centrality classes, and also consistent with the HG-PYTHIA model, which describes the event selection and geometry biases that affect the centrality determination in peripheral Pb$-$Pb collisions. The measurement is compared to next-to-leading order perturbative QCD calculations and to the measurements of isolated photons and Z${}^0$ bosons from the CMS experiment, which are all found to be in agreement.

arXiv comment45 pages, 17 captioned figures, 2 tables, authors from page 39, figures at http://alice-publications.web.cern.ch/node/11329

References in corpus (79)

• An Introduction to PYTHIA 8.2
• Experimental and Theoretical Challenges in the Search for the Quark Gluon Plasma: The STAR Collaboration's Critical Assessment of the Evidence from RHIC Collisions
• Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
• Quark Gluon Plasma an Color Glass Condensate at RHIC? The perspective from the BRAHMS experiment
• The PHOBOS Perspective on Discoveries at RHIC
• Tuning PYTHIA 8.1: the Monash 2013 Tune
• Performance of the ALICE Experiment at the CERN LHC
• Heavy Ion Collisions: The Big Picture, and the Big Questions
• Transverse momentum and collision energy dependence of high $p_T$ hadron suppression in Au+Au collisions at ultrarelativistic energies
• The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events
• First Results from Pb+Pb collisions at the LHC
• Centrality determination of Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV with ALICE
• The Path to Proton Structure at One-Percent Accuracy
• Performance of the ALICE VZERO system
• Alignment of the ALICE Inner Tracking System with cosmic-ray tracks
• Properties of hot and dense matter from relativistic heavy ion collisions
• Suppression pattern of neutral pions at high transverse momentum in Au+Au collisions at sqrt(s_NN) = 200 GeV and constraints on medium transport coefficients
• Cross section of isolated prompt photons in hadron-hadron collisions
• Centrality Dependence of Direct Photon Production in sqrt(s_NN) = 200 GeV Au+Au Collisions
• Production of charged pions, kaons and (anti-)protons in Pb-Pb and inelastic pp collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• Direct photon production in Pb-Pb collisions at $\sqrt{s_\rm{NN}}$ = 2.76 TeV
• Charged-particle nuclear modification factors in PbPb and pPb collisions at sqrt(s[NN]) = 5.02 TeV
• A new critical study of photon production in hadronic collisions
• Anisotropic flow of charged particles in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV
• Transverse momentum spectra and nuclear modification factors of charged particles in pp, p-Pb and Pb-Pb collisions at the LHC
• Measurement of the inclusive isolated prompt photon cross section in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
• Measurement of isolated photon production in pp and PbPb collisions at sqrt(sNN) = 2.76 TeV
• Measurement of jet suppression in central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• The ALICE experiment: a journey through QCD
• Measurement of the nuclear modification factor for inclusive jets in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector
• Neutral pion production with respect to centrality and reaction plane in Au+Au collisions at sqrt(s_NN)=200 GeV
• Study of W boson production in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV
• Measurement of direct photon production in p + p collisions at sqrt(s) = 200 GeV
• Quantitative constraints on the gluon distribution function in the proton from collider isolated-photon data
• Measurement of inclusive jet cross sections in pp and PbPb collisions at sqrt(s[NN]) = 2.76 TeV
• On the characterisation of the underlying event
• Study of Jet Shapes in Inclusive Jet Production in ppbar Collisions at sqrt{s} = 1.96 TeV
• Measurement of Direct Photons in Au+Au Collisions at sqrt(s_NN) = 200 GeV
• Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data
• Measurement of the Isolated Photon Cross Section in p-pbar Collisions at sqrt{s}=1.96 TeV
• Measurement of the cross section for inclusive isolated-photon production in $pp$ collisions at $\sqrt{s}=13$ TeV using the ATLAS detector
• Measurement of the Differential Cross Section for Isolated Prompt Photon Production in pp Collisions at 7 TeV
• Measurements of inclusive jet spectra in pp and central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• Measurement of Z boson Production in Pb+Pb Collisions at sqrt(s_NN)=2.76 TeV with the ATLAS Detector
• Measurement of the inclusive isolated prompt photon cross section in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector using 4.6 fb-1
• Measurement of the Isolated Prompt Photon Production Cross Section in pp Collisions at sqrt(s) = 7 TeV
• Measurement of the inclusive isolated prompt photon cross section in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector
• Quarks and Gluon Fragmentation Functions into Photons
• Absence of jet quenching in peripheral nucleus-nucleus collisions
• Centrality, rapidity and transverse momentum dependence of isolated prompt photon production in lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV measured with the ATLAS detector
• Study of Z production in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV in the dimuon and dielectron decay channels
• Inclusive prompt photon production in nuclear collisions at RHIC and LHC
• Jet quenching
• Sensitivity of isolated photon production at TeV hadron colliders to the gluon distribution in the proton
• Measurement of the Inclusive Isolated Prompt Photon Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using the CDF Detector
• Analysis of the apparent nuclear modification in peripheral Pb-Pb collisions at 5.02 TeV
• Combining Difficulty Ranking with Multi-Armed Bandits to Sequence Educational Content
• The Quark and Gluon Structure of the Proton
• Direct photon production at low transverse momentum in proton-proton collisions at $\sqrt{s}$ = 2.76 and 8 TeV
• Measurement of $W^{\pm }$ boson production in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector
• Measurement of differential cross sections for inclusive isolated-photon and photon+jet production in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• $Z$ boson production in Pb+Pb collisions at $\sqrt{s_{\text{NN}}}$= 5.02 TeV measured by the ATLAS experiment
• Measurement of the inclusive isolated photon production cross section in pp collisions at $\sqrt{s}$ = 7 TeV
• Measurement of the inclusive isolated-photon cross section in $pp$ collisions at $\sqrt{s}=13$ TeV using 36 fb${}^{-1}$ of ATLAS data
• Nonprompt direct-photon production in Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Constraints on the initial state of PbPb collisions via measurements of Z boson yields and azimuthal anisotropy at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV
• Isolated photon and photon+jet production at NNLO QCD accuracy
• Shadowing in inelastic nucleon-nucleon cross section?
• 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
• Performance of the ALICE Electromagnetic Calorimeter
• The production of isolated photons in PbPb and pp collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV
• Inclusive-photon production and its dependence on photon isolation in $pp$ collisions at $\sqrt{s}=13$ TeV using 139 fb${}^{-1}$ of ATLAS data
• Measurement of isolated photon-hadron correlations in $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV pp and p-Pb collisions
• Centrality dependence of electroweak boson production in PbPb collisions at the LHC
• The ALICE EMCal L1 trigger first year of operation experience
• Quenching of photon and pion spectra at intermediate RHIC energy
• W${}^{\pm }$-boson production in p$-$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV and PbPb collisions at $\sqrt{s_{NN}}=5.02$ TeV
• Direct photon production in d+A and A+A collisions at RHIC
• Measurement of the inclusive isolated-photon production cross section in pp collisions at $\sqrt{s}$ = 13 TeV

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