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.