Results are presented of a search for the Standard Model (SM) Higgs boson decaying into two photons at the Compact Muon Solenoid (CMS) experiment housed at the Large Hadron Collider (LHC), CERN. An excess of events is observed over the background expectation with a local significance of 5.7 (lower-case sigma), where the SM expectation is 5.2 (lower-case sigma), constituting a standalone discovery of the particle first observed by the ATLAS and CMS experiments in July 2012. Measurements of the particle's signal strength, mass and couplings are presented along with an analysis of its spin. The results show a high level of compatibility with the predictions for a SM Higgs boson. The observed state's signal strength relative to the SM expectation is found to be lower-case sigma/lower-case sigma_{\mathrm{SM}}=1.14^{+0.26}_{-0.23}$. The observed state's mass is found to be $124.72\pm 0.35$~GeV. The signal strength relative to the SM expectation when probing production mechanisms through fermionic modes only is 1.13^{+0.37}_{-0.31}, and from bosonic production modes only is 1.16^{+0.63}_{-0.57}. A spin-2 graviton, produced entirely by gluon fusion, is excluded at 94\%~C.L.~(92\% expected) and a spin-2 graviton, produced entirely by quark-antiquark annihilation, is excluded at 85\%~C.L.~(83\% expected).
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:656645 |
| Date | January 2014 |
| Creators | Kenzie, Matthew |
| Contributors | Dauncey, Paul |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/24976 |
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