title: Search for new physics with top quark pairs in the fully hadronic final state at the ATLAS experiment
creator: Kolb, Mathis
subject: ddc-530
subject: 530 Physics
description: Fully hadronic final states containing top quark pairs (tt) are investigated using proton-proton collision data at a center of mass energy of 13 TeV recorded in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider at CERN. The bucket algorithm suppresses the large combinatorial background and is used to identify and reconstruct the tt system. It is applied in three analyses.  A model independent search for new heavy particles decaying to tt using 36 fb^-1 of data is presented. The analysis concentrates on an optimization of sensitivity at tt masses below 1.3 TeV. No excess from the Standard Model prediction is observed. Thus, upper limits at 95% C.L. are set on the production cross section times branching ratio of benchmark signal models excluding e.g. a topcolor assisted technicolor Z'_TC2 in the mass range from 0.59 TeV to 1.25 TeV.   The prospects of a search for the production of the Higgs boson in association with tt using 33 fb^-1 of data recorded solely in 2016 are studied. The expected sensitivity based on statistical uncertainties implies that at least 950 fb^-1 of data would be required for an observation.   From the additionally conducted trigger study it is concluded that developments at trigger level are required to use the analysis strategy presented in future searches for new physics.
date: 2018
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/25702/1/thesis_kolb.pdf
identifier: DOI:10.11588/heidok.00025702
identifier: urn:nbn:de:bsz:16-heidok-257024
identifier:   Kolb, Mathis  (2018) Search for new physics with top quark pairs in the fully hadronic final state at the ATLAS experiment.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/25702/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng