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Title: Monte Carlo simulations for BSM physics and precision Higgs physics at the LHC
Author: Kuttimalai, Silvan Shiwa
ISNI:       0000 0004 5923 1639
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 2016
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Monte Carlo event generators are indispensable tools for the interpretation of data taken at particle collider experiments like the Large Hadron Collider (LHC), the most powerful particle collider to date. In this thesis, the general purpose Monte Carlo event generator Sherpa is used to implement a new simulation framework for models that go beyond the Standard Model of particle physics. This is achieved by means of an newly designed interface to a universal format for generic models and by extending existing functionalities in such a way as to handle a generic class of coupling structures that appear in many extensions of the Standard Model. Furthermore, an improved modeling of the dominant LHC Higgs pro- duction mechanism in the Standard Model is described and the effects of the improvements are quantified. The improved simulation that is implemented in Sherpa supplements the description of Higgs production at the LHC in terms of an effective Higgs-gluon interaction with finite top quark mass effects that restore a reliable description of the kinematics in events with large momentum transfers. Using this improved description of Higgs production at the LHC, this work demonstrates how the transverse momentum spectrum of the Higgs boson can be used to constrain models that modify the Higgs-gluon coupling. In addition, state-of-the-art Monte Carlo event generation techniques are used in order to assess the sensitivity of analysis strategies in the search for invisibly decaying Higgs bosons. In this analysis, it was found that previously neglected loop-induced contributions have a significant impact and it is demonstrated how multi-jet merging techniques can be used to obtain a reliable description of these contributions. Furthermore, the work presented in the last chapter of this thesis shows how jet substructure techniques can be used in order to search for rare Higgs decays into light resonances that decay further into hadrons. This analysis closes with a demonstration on how such an analysis can be used to constrain extensions of the Standard Model that feature multiple Higgs bosons.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available