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Title: Measurement of the polarisation of the W boson and application to supersymmetry searches at the Large Hadron Collider
Author: Sparrow, Alexander
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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This thesis gives an account of two analyses performed using data from the Compact Muon Solenoid experiment at the Large Hadron Collider. The first analysis measures the polarisation of W bosons with large transverse momentum using 36 pb⁻¹ of data collected in 2010. The second applies similar techniques to a search for supersymmetry in events containing a single lepton, jets and missing transverse energy. This analysis utilises 1.14 fb⁻¹ of data collected up to 2011. Background material related to the Standard Model, supersymmetry and the experimental apparatus are reviewed in detail. The W polarisation measurement is performed in both the W->ev and W->μv channels. The expected effect, a large dominance of the left-handed over the right-handed helicity state, is observed with a significance of 7.8σ for the W⁺ and 5.1σ for the W⁻ in the muon channel. Similar results are found in the electron channel and for a combined fit to both lepton channels. The second analysis conducts a search for supersymmetry in events containing a single lepton, jets and missing transverse energy. The search employs techniques developed for the W polarisation measurement to separate supersymmetry from Standard Model backgrounds. No deviation from the Standard Model is observed. A detailed statistical interpretation is performed and used to set limits within the Constrained Minimal Supersymmetric Standard Model as well as two simplified models.
Supervisor: Virdee, Tejinder ; Tapper, Alexander Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available