Results from studies on the commissioning of the Global Calorimeter Trigger (GCT)
of the CMS experiment are presented. Event-by-event comparisons of the hardware
with a bit-level software emulation are used to achieve 100% agreement for all trigger
quantities. In addition, a missing energy trigger based on jets is motivated using a
simulation study, and consequently implemented and commissioned in the GCT.
Furthermore, a templated-fit method for measuring the polarisation of W bosons
at the LHC in the “Helicity Frame” is developed, and validated in simulation. An
analysis of the first 3.2 pb−1 of
√
s = 7 TeV LHC data in the muon channel yields
values of (fL − fR)+ = 0.347 ± 0.070, f+
0 = 0.240 ± 0.176, and (fL − fR)− =
0.097 ± 0.088, f−
0 = 0.262 ± 0.196 for positive and negative charges respectively.
The errors quoted are statistical. A preliminary systematic study is also presented.