Inclusive and differential cross section measurements of top quark pair (tt¯) production in association with a photon (γ) are performed as a function of lepton, photon, top quark, and tt¯ kinematic observables, using data from proton-proton collisions at s=13 TeV, corresponding to an integrated luminosity of 138 fb−1, collected at the CERN LHC with the CMS detector. Events containing two leptons (electrons or muons) and a photon in the final state are considered. The fiducial cross section of tt¯γ is measured to be 137 ± 8 fb, in a phase space including events with a high momentum, isolated photon. The fiducial cross section of tt¯γ is also measured to be 56 ± 5 fb when considering only events where the photon is emitted in the production part of the process. Both measurements are in agreement with the theoretical predictions, of 126 ± 19 fb and 57 ± 5 fb, respectively. Differential measurements are performed at the particle and parton levels. Additionally, inclusive and differential ratios between the cross sections of tt¯γ and tt¯ production are measured. The inclusive ratio is found to be 0.0133 ± 0.0005, in agreement with the standard model prediction of 0.0127 ± 0.0008. The top quark charge asymmetry in tt¯γ production is also measured to be −0.012 ± 0.042, compatible with both the standard model prediction and with no asymmetry.

Inclusive and differential measurements of the ttγ cross section and the ttγ /tt cross section ratio in proton-proton collisions at √s = 13 TeV

Alexe, C.;Bruschini, D.;Ligabue, F.;
2026

Abstract

Inclusive and differential cross section measurements of top quark pair (tt¯) production in association with a photon (γ) are performed as a function of lepton, photon, top quark, and tt¯ kinematic observables, using data from proton-proton collisions at s=13 TeV, corresponding to an integrated luminosity of 138 fb−1, collected at the CERN LHC with the CMS detector. Events containing two leptons (electrons or muons) and a photon in the final state are considered. The fiducial cross section of tt¯γ is measured to be 137 ± 8 fb, in a phase space including events with a high momentum, isolated photon. The fiducial cross section of tt¯γ is also measured to be 56 ± 5 fb when considering only events where the photon is emitted in the production part of the process. Both measurements are in agreement with the theoretical predictions, of 126 ± 19 fb and 57 ± 5 fb, respectively. Differential measurements are performed at the particle and parton levels. Additionally, inclusive and differential ratios between the cross sections of tt¯γ and tt¯ production are measured. The inclusive ratio is found to be 0.0133 ± 0.0005, in agreement with the standard model prediction of 0.0127 ± 0.0008. The top quark charge asymmetry in tt¯γ production is also measured to be −0.012 ± 0.042, compatible with both the standard model prediction and with no asymmetry.
Inclusive and differential measurements of the $$ \textrm{t}\overline{\textrm{t}}\upgamma $$ cross section and the $$ \textrm{t}\overline{\textrm{t}}\upgamma /\textrm{t}\overline{\textrm{t}} $$ cross section ratio in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV
2026
Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
Hadron-Hadron Scattering; Particle and Resonance Production; Top Physics; Pair Production
   Advanced Multi-Variate Analysis for New Physics Searches at the LHC
   AMVA4NewPhysics
   European Commission
   Horizon 2020 Framework Programme - European Training Networks
   675440

   Fundamental properties and time-scan of QCD matter at high densities and temperature exposed by jet substructure in heavy ion collisions with CMS experiment at the LHC
   QCDHighDensityCMS
   European Commission
   Horizon 2020 Framework Programme - European Research Council - Consolidator Grant
   101002207

   Search for Higgs bosons decaying to charm quarks
   HIGCC
   European Commission
   Horizon 2020 Framework Programme - European Research Council - Consolidator Grant
   724704

   The strong interaction at the frontier of knowledge: fundamental research and applications
   STRONG-2020
   European Commission
   Horizon 2020 Framework Programme - Research and Innovation action
   824093

   International Training Network for Statistics in High Energy Physics and Society
   INSIGHTS
   European Commission
   Horizon 2020 Framework Programme - European Training Networks
   765710

   Direct and indirect searches for new physics in events with top quarks using LHC proton-proton collisions at the CMS detector
   LHCTOPVLQ
   European Commission
   Horizon 2020 Framework Programme - Standard European Fellowships
   752730

   Power to the LHC data: an ASYmptotically MOdel-independent measurement of the W boson mass
   ASYMOW
   European Commission
   Horizon 2020 Framework Programme - European Research Council - Consolidator Grant
   101001205

   INnovative TRiggEr techniques for beyond the standard model PhysIcs Discovery at the LHC
   INTREPID
   European Commission
   Horizon Europe Framework Programme - European Research Council - HORIZON ERC Grants
   101115353

   Majorana neutrino discovery strategy with CMS
   MajorNet
   European Commission
   Horizon 2020 Framework Programme - European Research Council - Starting Grant
   758316

   Future Artificial Intelligence Research
   FAIR
   MUR
   PNRR
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/170803
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