TY  - THES
AU  - Seidel, Markus
TI  - Precise measurement of the top-quark mass at the CMS experiment using the ideogram method
IS  - DESY-THESIS-2015-034
SN  - 1435-8085
PB  - Universität Hamburg
VL  - Dr.
CY  - Hamburg
M1  - PUBDB-2015-03093
M1  - DESY-THESIS-2015-034
T2  - DESY-THESIS
SP  - 203
PY  - 2015
N1  - Universität Hamburg, Diss., 2015
AB  - The mass of the top quark is measured using a sample of ttbar candidate events with one electron or muon and at least four jets in the final state, collected by CMS in proton-proton collisions at sqrts=8 TeV at the LHC. The candidate events are selected from data corresponding to an integrated luminosity of 19.7 fb^-1. For each event the top-quark mass is reconstructed from a kinematic fit of the decay products to a ttbar hypothesis. In order to minimize the uncertainties from jet energy corrections, the top-quark mass is determined simultaneously with a jet energy scale factor (JSF), constrained by the known mass of the W boson decaying to quark-antiquark pairs. A joint likelihood fit taking into account multiple interpretations per event - the ideogram method - is used. From the simultaneous fit, a top-quark mass of 172.15 +/- 0.19 (stat.+JSF) +/- 0.61 (syst.) GeV is obtained. Using an additional constraint from the determination of the jet energy scale in photon/Z+jet events yields m_t = 172.38 +/- 0.16 (stat.+JSF) +/- 0.49 (syst.) GeV. The results are discussed in the context of different event generator implementations. Possible kinematic biases are studied by performing the measurement in different regions of the phase space.
LB  - PUB:(DE-HGF)29 ; PUB:(DE-HGF)11
DO  - DOI:10.3204/DESY-THESIS-2015-034
UR  - https://bib-pubdb1.desy.de/record/222219
ER  -