Measurement of single top and ttbar production cross sections in association with a photon in proton-proton 
collisions at sqrt(s) = 13 TeV

CMS Physics Analysis Summaries
Report number	CMS-PAS-TOP-25-003
Title	Measurement of single top and ttbar production cross sections in association with a photon in proton-proton collisions at sqrt(s) = 13 TeV
Corporate author(s)	CMS Collaboration
Collaboration	CMS Collaboration
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; CMS
Abstract	Measurements of fiducial inclusive and differential cross sections for photon-associated production of single top quarks $\mathrm{t}\gamma\mathrm{q}$ and top quark pairs $\mathrm{t\bar{t}}\gamma$ are performed in proton--proton collisions at a center-of-mass energy of 13$~\mathrm{TeV}$. A sample of events is selected, containing a single isolated electron or muon, an isolated photon, and at least two jets, including one identified as originating from a $\mathrm{b}$ quark. The data were recorded with the CMS detector at the CERN LHC and correspond to an integrated luminosity of $138~\mathrm{fb}^{-1}$. A profile likelihood fit is employed to unfold the cross sections, account for systematic uncertainties, and determine the correlations between the two signal processes in a single global fit. The fiducial $\mathrm{t}\gamma\mathrm{q}$ and $\mathrm{t\bar{t}}\gamma$ cross sections are measured to be $237_{-17}^{+17}\,\mathrm{fb}$ and $1445_{-81}^{+81}\,\mathrm{fb}$, respectively, in a phase space requiring events with a high momentum, isolated photon. Differential measurements as a function of lepton, photon, light jet, and top quark kinematic observables are performed at the particle and parton levels. All results are found to be in good agreement with theoretical predictions.
Email contact: cms-pag-conveners-top@cern.ch Fulltext in PDF Figure_005-b Figure_009-c Figure_008-b Figure_008-c Figure_009-e Figure_008-a Figure_008-f Figure_008-g Figure_008-d Figure_008-e Figure_008-h Figure_009-h Figure_009-b Figure_003-a Figure_009-g Figure_003-b Figure_009-f Figure_009-d Figure_007-d Figure_005-a Figure_007-a Figure_007-c Figure_007-b Figure_001-d Figure_009-a Figure_006-a Figure_006-b Figure_006-c Figure_006-d Figure_002-a Figure_002-b Figure_004 Figure_001-c Figure_001-b Figure_001-a Additional information for the analysis (restricted access)