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Many searches for new physics involve signatures of missing transverse energy (MET), which signify presence of weakly interacting particles, such as neutrinos or dark matter candidates. To reliably establish presence of new signal, excellent resolution of MET reconstruction is crucial, to separate signals of new physics from known processes, and to measure the parameters of decays of such particles. In 2012 the LHC will attempt to collect as much data as possible by raising number of simultaneous collisions in each bunch crossing, expected average number of collisions being around 30 per crossing. This increased interaction rate will provide more chances to create rare particles. The large occupancy of events will however have a detrimental effect on MET reconstruction, reducing the sensitivity of searches of new physics, since MET resolution will be significantly reduced. The project will work to improving the MET reconstruction performance in CMS, by optimizing the reconstruction parameters used in CMS, and fine-tuning the thresholds of objects used in the MET calculation. The effect will be first studied in high occupancy events using MC and deducing the correlation with generator level quantities, and the results will be compared to CMS data. The improvements in the MET reconstruction will then be tested in the context of searches of new physics in events involving MET, such as SUSY searches. |
