Abstract
A new set of measurements of the top quark mass are presented, based on the proton-proton data recorded by the CMS experiment at the LHC at sqrt(s) = 8 TeV corresponding to a luminosity of 19.7 inverse femtobarns. The top quark mass is measured using the lepton + jets, all-jets and dilepton decay channels, giving values of 172.35 +/- 0.16 (stat) +/- 0.48 (syst) GeV, 172.32 +/- 0.25 (stat) +/- 0.59 (syst) GeV, and 172.82 +/- 0.19 (stat) +/- 1.22 (syst) GeV, respectively. When combined with the published CMS results at sqrt(s) = 7 TeV, they provide a top quark mass measurement of 172.44 +/- 0.13 (stat) +/- 0.47 (syst) GeV. The top quark mass is also studied as a function of the event kinematical properties in the lepton + jets decay channel. No indications of a kinematic bias are observed and the collision data are consistent with a range of predictions from current theoretical models of t t-bar production.
Highlights
The mass of the top quark is one of the fundamental parameters of the standard model (SM)
The measurements from the 1D and hybrid analyses are m1t D 1⁄4 172.56 Æ 0.12ðstatÞ Æ 0.62ðsystÞ GeV; mht yb 1⁄4 172.35 Æ 0.16ðstat þ JSFÞ Æ 0.48ðsystÞ GeV: the hybrid approach delivers the most precise measurement of the methods studied for the lepton þ jets channel with a total uncertainty of 0.51 GeV
The top quark mass has been measured in the lepton þ jets, all-jets and dilepton decay channels, giving values of 172.35 Æ 0.16ðstatÞ Æ
Summary
The mass of the top quark (mt) is one of the fundamental parameters of the standard model (SM). The most precise measurements of mt have been derived from combinations of the results from the CDF and D0 experiments at the Tevatron, and ATLAS and CMS at the CERN LHC. The current four experiment combination has not been updated since 2013 and does not include the latest Tevatron and LHC measurements, in particular the measurement from ATLAS using a combination of the lepton þ jets and dilepton channels [9]. The value of mt used in the simulation is 172.5 GeV and the nominal jet energy scale is applied. The all-jets results for mt and the JSF are compared in Fig. 6 which shows the twodimensional statistical likelihoods obtained from data in the 2D and hybrid cases and mt from the 1D analysis
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