Date of Award

2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Physics & Astronomy

First Advisor

Elliot Lipeles

Abstract

Evidence for the Higgs boson is presented in the \hwwlnln\ channel in the ATLAS

detector with 20.3/fb of 8 TeV and 4.5/fb of

7 TeV proton-proton collisions at the Large Hadron Collider (LHC). The H$\rightarrow$WW analysis is one of the

three Higgs boson decay channels used by the ATLAS collaboration in combination to discover the

Higgs boson. As the LHC increased its instantaneous luminosity,

the average number of collisions per proton bunch crossing, called pileup, was

increased to around 20. The techniques presented in this thesis mitigate the

effects of pileup such as interaction vertex matching for event level

quantities such as the missing transverse momentum.

Optimization procedures for lepton identification, which is crucial for

the semi-leptonic W decays, are presented and methods to model the

fake leptons which are quarks

and gluons imitating leptons from W and Z bosons. Finally,

performance projections for future LHC running

conditions are explored to inform funding agencies.

These techniques

are applied to the gluon-gluon fusion (ggF) and vector boson fusion (VBF)

production of the Higgs boson on the LHC. Both production modes were

measured to be consistent with the Standard Model expectations.

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