Associated Production of a Top Quark and a Z Boson in pp Collisions at 13 TeV Using the ATLAS Detector

Introduction......Page 7
The Standard Model in a nutshell......Page 9
Hard scattering, factorisation and cross-sections......Page 12
Collisions and particle decays......Page 13
Kinematics......Page 14
Top-quark properties......Page 15
Top-quark production......Page 16
Rare processes involving top quarks......Page 17
The Large Hadron Collider......Page 21
The ATLAS detector......Page 22
Inner detector......Page 24
Calorimeters......Page 25
Trigger and data acquisition system......Page 27
Physics object reconstruction in ATLAS......Page 28
Electrons......Page 29
Muons......Page 31
Jets......Page 33
ETmiss reconstruction......Page 37
Data sample......Page 39
Monte Carlo simulation......Page 40
MC samples for processes of interest......Page 41
Reweighting of Monte Carlo simulated events......Page 42
t Z q trilepton final state......Page 45
Sources of background......Page 46
Event preselection......Page 49
Signal region definition......Page 50
Background Estimation......Page 51
Non-prompt lepton background estimation......Page 53
Prediction and observation comparison in the signal and validation regions......Page 63
Signal and background separation......Page 71
Multivariate analysis techniques: artificial NN......Page 72
NN training to separate t Z q......Page 73
Systematic uncertainties......Page 77
Sources of systematic uncertainties......Page 79
Systematic uncertainties evaluation......Page 82
Signal Extraction - Binned Likelihood Fit......Page 85
Expected fit results......Page 89
Observed fit results......Page 92
Discussion of the results......Page 97
Conclusions......Page 101
Contol plots for basic kinematic variables in the SR......Page 103
Control plots in the background dominated region......Page 107
Control plots in the signal dominated region......Page 109
Control Plots in the diboson VR......Page 111
Additional control plots in the t 0mu-0mut VR......Page 112
Event yields for the t 0mu-0mut and diboson VR......Page 113
Additional information on systematic uncertainties......Page 115
Additional Studies on t 0mu-0mut background estimation......Page 123
Additional Studies on Z +jets background estimation......Page 124
t Z q event displays......Page 129
Bibliography......Page 133
Acknowledgements......Page 143