Measurement of the differential $$\hbox {t}\overline{\hbox {t}}$$ t 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

Abstract

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 (

$$\hbox {t}\overline{\hbox {t}}$$

t

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

$$\,\text {Ge}\hspace{-.08em}\text {V}$$

Ge

V

. The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138

$$\,\text {fb}^{-1}$$

fb

- 1

. The differential

$$\hbox {t}\overline{\hbox {t}}$$

t

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

$$173.06 \pm 0.84\,\text {Ge}\hspace{-.08em}\text {V} $$

173.06 ± 0.84

Ge

V

.