Abstract
This paper presents measurements of toverline{t} production in association with additional b-jets in pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 36.1 fb−1. Fiducial cross-section measurements are performed in the dilepton and lepton-plus-jets toverline{t} decay channels. Results are presented at particle level in the form of inclusive cross-sections of toverline{t} final states with three and four b-jets as well as differential cross-sections as a function of global event properties and properties of b-jet pairs. The measured inclusive fiducial cross-sections generally exceed the toverline{t}boverline{b} predictions from various next-to-leading-order matrix element calculations matched to a parton shower but are compatible within the total uncertainties. The experimental uncertainties are smaller than the uncertainties in the predictions. Comparisons of state-of-the-art theoretical predictions with the differential measurements are shown and good agreement with data is found for most of them.
Highlights
Measurements of the production cross-section of top-antitop quark pairs with additional jets provide important tests of quantum chromodynamics (QCD) predictions
This paper presents measurements of ttproduction in association with additional b-jets in pp collisions at the LHC at a centre-of-mass energy of 13 TeV
Even though the aim is to improve the modelling of QCD production of additional b-jets in ttevents, this analysis measures their production without separating the different production channels such as tt-associated Higgs production (ttH) or ttin association with a vector boson, for example the ttZ process shown in figure 1c
Summary
Measurements of the production cross-section of top-antitop quark pairs (tt) with additional jets provide important tests of quantum chromodynamics (QCD) predictions. Even though the aim is to improve the modelling of QCD production of additional b-jets in ttevents, this analysis measures their production without separating the different production channels such as ttH or ttin association with a vector boson (ttV ), for example the ttZ process shown in figure 1c. The results are obtained as a function of the transverse momentum (pT) of each of the b-jets, the scalar sum of the pT of the lepton(s) and jets in the events (HT) and of only jets in the events (HThad) and as a function of the b-jet multiplicity (Nb-jets) This analysis does not attempt to identify the origin of the b-jets, i.e. it does not distinguish between additional b-jets and b-jets that come from the top-quark decays.
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