Measurement of the differential $\mathrm{t\bar{t}}$ production cross section as a function of the jet mass and extraction of the top quark mass in hadronic decays of boosted top quarks

TL;DR

This paper measures the distribution of jet mass in boosted top quark decays to determine the top quark mass with high precision, utilizing CMS data and advanced calibration and modeling techniques.

Contribution

It introduces a novel method for extracting the top quark mass from jet mass distributions in boosted top decays with improved accuracy.

Findings

Top quark mass measured as 173.06 ± 0.84 GeV.

Enhanced calibration reduces jet mass scale uncertainties.

Improved modeling of final state radiation increases measurement precision.

Abstract

A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton+jets channel of top quark pair production ($\mathrm{t\bar{t}}$) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400 GeV. The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138 fb$^{-1}$. The differential $\mathrm{t\bar{t}}$ production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modelling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of 173.06 $\pm$ 0.84 GeV.