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Search for the Higgs Boson decaying to a b quark pair produced in association with a W Boson using missing transverse energy triggered events at ATLAS

Allbrooke, Benedict Marc Miller (2015)
Ph.D. thesis, University of Birmingham.

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The WH → \(lv\)bb production and decay mode of the standard model Higgs Boson is searched for using the 2012 LHC proton-proton data recorded by the ATLAS detector at a centre-of-mass energy √s=8 TeV. Events containing W → μ\(v\) that fail muon triggers are recovered using a novel technique of recording these events with missing transverse energy based triggers.

Two analyses are employed, one based on simple selection criteria to enhance the signal-to-background ratio and one that uses more complex multivariate techniques to separate signal from background. Both analyses exploit the different signal-to-background ratios in regions of the reconstructed W transverse momentum and b-jet tagging categorisation. The events recorded using the missing transverse energy triggers are analysed exclusively as well as merged with the events recorded using lepton triggers to improve the sensitivity of the final analyses.

The multivariate merged analysis is found to be the more sensitive of the two analyses, gaining 18.5% compared to the equivalent cut-based analysis. The observed (expected) 95% CL limit for the WH → \(lv\)bb mode is found to be 2.507 (1.369) and the observed (expected) significance is 1.905 (1.534). The final value of the signal strength for WH → \(lv\)bb is μ=1.231± \[^{0.733}_{0.665}\] which is consistent with the Standard Model expectation.

Type of Work:Ph.D. thesis.
Supervisor(s):Watson, Alan and Thompson, Paul
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Physics and Astronomy
Subjects:QC Physics
Institution:University of Birmingham
ID Code:5681
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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