Abstract
A top quark mass measurement is performed using 35.9{,text {fb}^{-1}} of LHC proton–proton collision data collected with the CMS detector at sqrt{s}=13,text {TeV} . The measurement uses the {mathrm {t}overline{mathrm {t}}} all-jets final state. A kinematic fit is performed to reconstruct the decay of the {mathrm {t}overline{mathrm {t}}} system and suppress the multijet background. Using the ideogram method, the top quark mass (m_{mathrm {t}}) is determined, simultaneously constraining an additional jet energy scale factor (text {JSF}). The resulting value of m_{mathrm {t}} =172.34pm 0.20,text {(stat+JSF)} pm 0.70,text {(syst)} ,text {GeV} is in good agreement with previous measurements. In addition, a combined measurement that uses the {mathrm {t}overline{mathrm {t}}} lepton+jets and all-jets final states is presented, using the same mass extraction method, and provides an m_{mathrm {t}} measurement of 172.26pm 0.07,text {(stat+JSF)} pm 0.61,text {(syst)} ,text {GeV} . This is the first combined m_{mathrm {t}} extraction from the lepton+jets and all-jets channels through a single likelihood function.
Highlights
The top quark [1,2] is the most massive known fundamental particle and its mass mt is an important parameter of the standard model (SM) of particle physics
The hybrid measurement of 172.34 ± 0.20 ± 0.43 (CR+early resonance decays (ERD)) ± 0.55 GeV is the main result of this analysis, since it is constructed to provide the smallest uncertainty
Because of the larger data sample used in this analysis, the statistical uncertainty is reduced with respect to the result of mt√= 172.32 ± 0.25 ± 0.59 GeV obtained at s = 8 TeV
Summary
The top quark [1,2] is the most massive known fundamental particle and its mass mt is an important parameter of the standard model (SM) of particle physics. The two bottom quarks and the four light quarks from the tt decay are all required to be physically separated in the laboratory frame of reference, and the nominal experimental signature is characterized by six jets in the detector. This final state provides the largest branching fraction of all tt decays, this measurement of mt is challenging, because of the large background from multijet production. A measurement using both tt all-jets and lepton+jets events is presented here This is possible since the two measurements use the same mass extraction method, so a single likelihood can be used, rather than just combining. This is the first report of a combined mt measurement in the lepton+jets and all-jets final states using a single likelihood function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
