Yoshikazu Nagai

The Quest for the Origin of Mass: Search for the Standard Model Higgs Boson in 1.96-tev Proton-antiproton Collisions Yoshikazu Nagai

"The Standard Model" of particle physics is a description of the fundamental particles, the quarks and leptons, and the forces between them. The Standard Model also explains the origin of mass, which predicts the existence of the Higgs boson, the last undetected particle in the Standard Model. This thesis presents a search for the Standard Model Higgs boson in the "H ->bb" decay channel in 1.96 TeV proton-antiproton collisions. This search is based on the data corresponding to an integrated luminosity of 4.3/fb collected by the CDF II detector at the Fermilab Tevatron Collider. To improve this search sensitivity, sophisticated multivariate techniques are employed. Through the use of these techniques, the analysis achieves an observed (expected) 95% confidence level upper limit of 5.26 (3.98) times the theoretically expected production cross section for the Standard Model Higgs boson with a mass of 115 GeV/c^2. This result represents a substantial improvement in sensitivity over the previous result, the increase in sensitivity is 26%.