Factors influencing the signal sensitivity in searches for Z' → ThadThad at √s = TeV with the ATLAS detector
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Date
2015-02-06
Authors
Hsu, Catherine
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Abstract
The Z' gauge boson is a hypothetical neutral particle of spin-1 appearing in many theories
beyond the Standard Model. In the context of the Z' boson of the Sequential Standard
Model in the hadronic decay channel Z' ThadThad, this project investigates improving the
sensitivity of the analysis. It is important in the analysis to have high signal e ciency
and to be able to distinguish against background processes, thus this project begins with
an investigation into new triggers and their combinations that aim to improve the signal
e ciency, followed by a study to improve the tau identi cation using tracking. Monte Carlo samples were compared with the
data sample for various cut-based variables to investigate which of the variables o er a good
discrimination power against the multijet background. The signi cance of each trigger and
trigger combinations are shown, as well as the performance of di erent techniques and ideas
used to improve the tau identi cation using tracking.
Since it is important in this project to be able to reconstruct a tau lepton from its hadronic
decay products, this dissertation takes the opportunity to present preliminary results on the
study of the light collection uniformity and response in the crack scintillation counters of the
ATLAS hadronic tile calorimeter as part of the contribution towards the detector upgrade.
Description
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. August 11, 2014.