Measurement of the top quark mass with lepton+jets final states using pp collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports a precise measurement of the top quark mass using proton-proton collision data at 13 TeV, employing a kinematic fit and ideogram method to analyze lepton+jets events with detailed calibration and systematic studies.

Contribution

The study introduces a measurement of the top quark mass at 13 TeV using a combined kinematic fit and ideogram method with simultaneous jet energy scale calibration, improving precision and robustness.

Findings

Top quark mass measured as 172.25 GeV with 0.62 GeV systematic uncertainty.

No bias observed in the measurement across different event kinematics.

Results are consistent with previous measurements and Standard Model predictions.

Abstract

The mass of the top quark is measured using a sample of $\mathrm{t\overline{t}}$ events collected by the CMS detector using proton-proton collisions at $\sqrt{s} =$ 13 TeV at the CERN LHC. Events are selected with one isolated muon or electron and at least four jets from data corresponding to an integrated luminosity of 35.9 fb$^{-1}$. For each event the mass is reconstructed from a kinematic fit of the decay products to a $\mathrm{t\overline{t}}$ hypothesis. Using the ideogram method, the top quark mass is determined simultaneously with an overall jet energy scale factor (JSF), constrained by the mass of the W boson in $\mathrm{q\overline{q}'}$ decays. The measurement is calibrated on samples simulated at next-to-leading order matched to a leading-order parton shower. The top quark mass is found to be 172.25 $\pm$ 0.08 (stat+JSF) $\pm$ 0.62 (syst) GeV. The dependence of this result on the kinematic properties of the event is studied and compared to predictions of different models of $\mathrm{t\overline{t}}$ production, and no indications of a bias in the measurements are observed.