Yau Wong, Kaven Henry: Measurement of the top-quark mass and the ttZ cross section in ATLAS: the tt dilepton way. - Bonn, 2015. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-40499
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-40499,
author = {{Kaven Henry Yau Wong}},
title = {Measurement of the top-quark mass and the ttZ cross section in ATLAS: the tt dilepton way},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2015,
month = jul,

note = {A measurement of the top-quark mass and the ttZ cross section is performed using 4.6 fb-1 and 20.3 fb-1 of data from proton-proton collisions collected with the ATLAS detector at the LHC. The top-quark mass is measured in the tt eµ channel using the mean value of the mT2 variable with the calibration curve method to obtain the first top-quark mass measurement in the dilepton channel using the ATLAS detector: mtop=175.2 ± 1.6 (stat.) ± 3.1 (syst.) GeV.
Improvements in the computation of the systematic uncertainty, the measurement method and the inclusion of the tt ee and µµ channels result in a significant increase in the precision of the measurement, leading to a measured top-quark mass of mtop=173.7 ± 0.8 (stat.) ± 1.8 (syst.) GeV. The use of the mT2perp variable is also studied, providing an additional mass measurement with similar uncertainty: mtop=173.3 ± 0.7 (stat.) ± 1.7 (syst.) GeV.
A ttZ cross-section measurement is performed in the ttZ → 4ℓ channel using a likelihood fit to five signal regions and one ZZ control region used to determine the normalization of the main background from data. Seven events are selected in data and, from the result of the likelihood fit, a ttZ cross section of sttZ = 0.32+0.18-0.14 (stat.) +0.12-0.05 (syst.) pb is measured, which is compatible with the Standard Model prediction for proton-proton collisions at 8 TeV.},

url = {https://hdl.handle.net/20.500.11811/6491}

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