Search for the Higgs Boson in the ZZ --> ℓℓvv channel with CMS

Abstract

The Standard Model (SM) of particle physics is a quantum field theory of the strong, weak, and electromagnetic interactions. It successfully describes a large majority of observed phenomena at microscopic scales. The key issue that remains to be addressed is the mechanism for electroweak symmetry breaking (EWSB). Without EWSB in the theory, the massive weak force mediators - the W and Z bosons, are required to be massless to satisfy gauge symmetry. To incorporate EWSB into the SM, the Higgs mechanism is invoked and introduces a scalar field, the Higgs field, that couples to the W and Z bosons and gives them mass. Additionally, the SM postulates that the fundamental fermions acquire mass through interactions with the Higgs field. Observation of the field quantum, the Higgs boson, would greatly validate our ideas on electroweak symmetry breaking and complete the table of fundamental particles predicted by the Standard Model. If it exists, the Higgs boson has eluded detection for decades. A primary objective of the Large Hadron Collider (LHC) project is to make a definitive statement about the existence of the Higgs boson. The LHC provided proton-proton collisions at [square root of]s = 7 TeV for the 2011 run. The search for the SM Higgs with the 2011 dataset represented the first major foray into the search effort by the LHC project. This thesis presents a search for the SM Higgs boson in the ZZ -->2ℓ2v channel from the analysis of 4.9 fb-1 of data collected with the Compact Muon Solenoid (CMS) detector at the LHC. Overviews of electroweak theory and of Higgs production at the LHC are given, followed by descriptions of the CMS detector and the algorithms for event reconstruction. A measurement of the inclusive cross section for Z boson production is presented as a validation on the measured efficiencies of the electron and muon reconstruction and selection requirements. Lastly, the Higgs search analysis and results are presented.