PhD Thesis Defenses

b-jet identification and searches for supersymmetry, dark matter and Higgs boson pair production with the ATLAS experiment

The Large Hadron Collider (LHC) is the largest and most powerful accelerator in the world. Proton bunches rotating in opposite directions are accelerated to 6.5 TeV inside the LHC ring and collided at four different points around the ring with an energy of 13 TeV. The ATLAS detector is a general purpose particle physics detector built around one of the collision points and is used to study the products of the high energy proton-proton collisions.

The identification of jets containing b hadrons (b-jets) is an important part of many physics analyses, including those presented in this thesis. The calibration of the b-jet identification algorithms is performed with data. The first part of this thesis describes the method to calibrate the probability of a light-flavour or gluon jet to be mistakenly identified as a b-jet. The second part presents a search for new phenomena in events with top quark pairs and large missing transverse energy using the full LHC Run 2 dataset. No evidence for physics beyond the Standard Model is found and the analysis is instead used to exclude various extensions of the Standard Model. The third part of the thesis describes an effective field theory approach to Higgs boson pair production.