Abstract
A search for the standard model production of four top quarks (pp → mathrm{t}overline{mathrm{t}}mathrm{t}overline{mathrm{t}} ) is reported using single-lepton plus jets and opposite-sign dilepton plus jets signatures. Proton-proton collisions are recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV in a sample corresponding to an integrated luminosity of 35.8 fb−1. A multivariate analysis exploiting global event and jet properties is used to discriminate mathrm{t}overline{mathrm{t}}mathrm{t}overline{mathrm{t}} from mathrm{t}overline{mathrm{t}} production. No significant deviation is observed from the predicted background. An upper limit is set on the cross section for mathrm{t}overline{mathrm{t}}mathrm{t}overline{mathrm{t}} production in the standard model of 48 fb at 95% confidence level. When combined with a previous measurement by the CMS experiment from an analysis of other final states, the observed signal significance is 1.4 standard deviations, and the combined cross section measurement is {13}_{-9}^{+11} fb. The result is also interpreted in the framework of effective field theory.
Highlights
A search for the standard model production of four top quarks is reported using single-lepton plus jets and opposite-sign dilepton plus jets signatures
This paper presents a new search in the single-lepton (SL) (μ, e)+jets and oppositesign dilepton (DL) (μ+μ−, μ±e∓, or e+e−)+jets tttt decay channels using pp collisions at 13 TeV collected by the CMS experiment in 2016 and corresponding to an integrated luminosity of 35.8 fb−1
The systematic uncertainties attributed to the trigger or specific to the jet or lepton reconstruction were treated as fully correlated among the different final states
Summary
The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter, and a brass and scintillator hadron calorimeter, each composed of a barrel and two endcap sections. Forward calorimeters extend the pseudorapidity coverage (η) provided by the barrel and endcap detectors. Muons are measured in gas-ionization detectors embedded in the steel flux-return yoke outside the solenoid, in the range |η| < 2.4. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the relevant kinematic variables, can be found in ref. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the relevant kinematic variables, can be found in ref. [24]
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