Measurement of differential $\mathrm{t\bar{t}}$ production cross sections using top quarks at large transverse momenta in pp collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports a measurement of differential top quark pair production cross sections at high transverse momentum in proton-proton collisions at 13 TeV, comparing results with theoretical models.

Contribution

First measurement of differential $ ext{t}ar{ ext{t}}$ cross sections at large transverse momenta using CMS data at 13 TeV, with detailed comparison to theoretical predictions.

Findings

Observed cross sections are lower than theoretical predictions.

Normalized differential distributions agree well with models.

Results provide insights into top quark production at high energies.

Abstract

A measurement is reported of differential top quark pair ($\mathrm{t\bar{t}}$) production cross sections, where top quarks are produced at large transverse momenta. The data collected with the CMS detector at the LHC are from pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The measurement uses events where at least one top quark decays as t $\to$ Wb $\to$ qq'b and is reconstructed as a large-radius jet with transverse momentum in excess of 400 GeV. The second top quark is required to decay either in a similar way, or leptonically, as inferred from a reconstructed electron or muon, a bottom quark jet, and a missing transverse momentum due to the undetected neutrino. The cross section is extracted as a function of kinematic variables of individual top quarks or of the $\mathrm{t\bar{t}}$ system. The results are presented at the particle level, within a region of phase space close to that of the experimental acceptance, and at the parton level, and are compared to various theoretical models. In both decay channels the observed absolute cross sections are significantly lower than the predictions from theory, while the normalized differential measurements are well described.