Abstract
Measurements of differential and double-differential cross sections of top quark pair ($\text{t}\overline{\text{t}}$) production are presented in the lepton+jets channels with a single electron or muon and jets in the final state. The analysis combines for the first time signatures of top quarks with low transverse momentum $p_\text{T}$, where the top quark decay products can be identified as separated jets and isolated leptons, and with high $p_\text{T}$, where the decay products are collimated and overlap. The measurements are based on proton-proton collision data at $\sqrt{s} = $ 13 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 137 fb$^{-1}$. The cross sections are presented at the parton and particle levels, where the latter minimizes extrapolations based on theoretical assumptions. Most of the measured differential cross sections are well described by standard model predictions with the exception of some double-differential distributions. The inclusive $\text{t}\overline{\text{t}}$ production cross section is measured to be $\sigma_{\text{t}\overline{\text{t}}} = $ 791 $\pm$ 25 pb, which constitutes the most precise measurement in the lepton+jets channel to date.
Highlights
Precision measurements of top-quark pair production are important tests of the standard model (SM), since the top quark plays an exceptional role; it is the heaviest known particle and the only quark that can be observed before hadronization
For the MATRIX, POWHEG+HERWIG, and MG5_aMC@NLO+PYTHIA simulations, we consider the dominant sources of matrix element scales and parton distribution functions (PDFs) uncertainties
For the parton-level measurements, similar p values are obtained for POWHEG+PYTHIA with the CUETP8M2T4 and CP5 tunes and POWHEG+HERWIG, while the description by MG5_aMC@NLO+PYTHIA is slightly worse
Summary
Precision measurements of top-quark pair (tt) production are important tests of the standard model (SM), since the top quark plays an exceptional role; it is the heaviest known particle and the only quark that can be observed before hadronization. Measurements of differential tt production cross sections are presented by the CMS Collaboration using e=μ þ jets events—i.e., with a single electron or muon and jets in the final state. This analysis is based on an integrated luminosity of 137 fb−1 at. At the parton and particle levels, we measure the differential cross sections as a function of the following variables: pTðthÞ, pTðtlÞ, and their scalar sum ST; the higher pTðthighÞ and the lower pTðtlowÞ transverse momenta of the top quarks; the rapidities jyðthÞj, jyðtlÞj and the rapidity differences Δjyt= ̄tj 1⁄4 jyðtÞj − jyðtÞj, jΔyt= ̄tj1⁄4jyðtÞ−yðtÞj; and the angle between the top quarks in the transverse plane Δφt= ̄t. Tabulated results are provided in HEPData [21]
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