CMS ECAL intercalibration with electrons from W and Z decays and Search for the Standard Model Higgs boson in the H > WW > lvqq channel with the CMS detector

The usage of isolated electrons from W and Z leptonic decays for the intercalibration of the CMS ECAL single channel response is described. The statistics of 5 fb−1, collected at LHC in 2011 at sqrt(s)=7 TeV, allowed to reach a statistical precision of about 1% in the central part of the ECAL barrel and about 4% in the ECAL endcaps. The results obtained with this method are combined with others, and the impact on the Higgs to di-photon search is shown. Subsequently, the thesis describes the search strategy for the Higgs boson in the H > WW > lvqq final state. The results are based on a data sample corresponding to an integrated luminosity of 17 fb−1 of proton-proton collisions accumulated during the 2011-2012 LHC run. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges [215 − 490] + [525 − 600] GeV.