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Title: Investigation of the discovery potential of a Higgs boson in the tt̄H⁰, H⁰→bb̄ channel with the ATLAS experiment
Author: Bernius, C.
ISNI:       0000 0004 2728 7590
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2010
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The production of a light Standard Model Higgs boson in association with a top-quark pair at the Large Hadron Collider (LHC) is studied in a simulation of the multipurpose ATLAS experiment. The Higgs boson is assumed to decay into a b\bar{b} pair, and the top-quark pair to decay semi-leptonically. The main background process for this channel is the production of t\bar{t} events, which can be divided into reducible and irreducible components. In the process of generating these components separately, an overlap of events is created through the addition of b-quarks to t\bar{t} events via parton showering in the t\bar{t}X sample. These events are already included in the matrix-element cross-section calculation for the t\bar{t}b\bar{b} sample. A new procedure for the overlap removal is presented in this thesis. Two analyses are studied, where one aims at the full reconstruction of the nal state using a cut-based approach. Recently, this way of reconstructing the t\bar{t}H^{o}(H^{o}\rightarrow b\bar{b}) process has been found to be extremely challenging. The other analysis is based on a new method employing state-of-the-art jet reconstruction and decomposition techniques where the t\bar{t} pair and the Higgs boson are required to have large transverse momenta and can therefore be reconstructed as massive Higgs and top jets. A recent phenomenological study has shown that the t\bar{t}H^{o} process can be recovered as a promising search channel for a low mass Standard Model Higgs boson around 120 GeV using this approach. Finally, to enhance the sensitivity of the t\bar{t}H^{o} channel, a combination of the two analyses is presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available