Search for a Standard Model Higgs Boson in CMS via Vector Boson Fusion in the $H \to WW \to lvlv$ channel and Optimization of ENergy Reconstruction in CMS using Test Beam 2006 Data

One of the goals of the LHC is to test the existence of the Higgs boson. This thesis presents a study of the potential to discover the Standard Model Higgs boson in the vector boson fusion *VBF) channel for the Higgs mass range 120-200 GeV/c^2. The decay of Higgs bosons into the WW* final state with both W bosons decaying leptonically is considered. The main backgrounds are ttbar+j and W+W-jj. This study, based on a full simulation of the CMS detector at the LHC, shows that a 5 sigma discovery can be done with an integrated luminosity of 12-72 fb^-1 for 130-200 GeV/c^2 Higgs bosons. Due to the uncertainties in the backgrounds, it is important to measure the backgrounds from data. This study shows that the major background can be measured directly to 7% with 30 fb^-1. After discovering the Higgs boson, it will be crucial to probe its physical properties. A method to measure the Higgs boson mass using transverse mass template distributions is investigated in the VBF channel. The performance of the combined CMS electromagnetic and hadronic calorimeters (EB+HB) was measured at the H2 test beam at the CERN SPS during 2006 with various particles in a large momentum range, 1-350 GeV/c. Another major contribution of this thesis is developing the method to optimize the energy reconstruction for the combined EB+HB system with which the corrected responses become 100% with 6% fluctuation and the stochastic resolution is improved from 111% to 94%.