The Standard Model (SM) of Particle Physics has proven to be an incredible mathematical framework for describing the observed elementary particles that make up the Universe and the way in which they interact through the fundamental forces of nature. The discovery of the Higgs boson in 2012 by both the Compact Muon Solenoid (CMS) experiment, and A Toroidal LHC Apparatus (ATLAS), the two general-purpose detectors at the Large Hadron Collider (LHC), was the latest confirmation of the theory. Although the SM has been enormously successful in accurately predicting the results of many measurements, there are still ways in which it is incomplete. Many Beyond the Standard Model (BSM) theories have been developed which attempt to add to or modify the SM to remove these limitations. A common feature in many BSM theories is an extended Higgs sector with more than one Higgs field producing multiple Higgs bosons, some of which are electrically charged. This thesis presents a search for a charged Higgs boson at the LHC using data collected by the CMS detector. The search was performed with 19.7 $fb^{-1}$ of data collected by CMS during the 2012 LHC run period where protons were collided at a center of mass energy of $8~\TeV$. The charged Higgs boson is produced in association with a top quark, and it itself is presumed to decay into a top-bottom quark pair nearly 100\% of the time. Final states with a single muon or single electron are selected to detect the presence of charged Higgs bosons. Upper limits at the 95\% confidence level on charged Higgs boson production cross section times the $H^\pm\rightarrow tb$ branching fraction are derived for a charged Higgs boson in the mass range 180 -- 600~\GeV. Across the mass range studied, no excess over the SM was measured. Limits on the production cross section times branching fraction are set between 2.4 $pb$ for low mass charged Higgs, and 0.2 $pb$ for high mass charged Higgs.
Garabedian, Alex E.,
"A Search For Heavy Charged Higgs Bosons in the CMS Experiment"
(2016).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0JQ0ZFP
