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Observation and measurement of the Higgs-like boson at 125 GeV in the two-photon decay channel with the CMS experiment

Posted on:2014-08-01Degree:Ph.DType:Thesis
University:Princeton UniversityCandidate:Quan, XiaohangFull Text:PDF
GTID:2450390005497351Subject:Molecular physics
Abstract/Summary:
We present results for the search for the Standard Model Higgs boson in the two-photon channel using the full 2011+2012 dataset recorded by the CMS experiment at the LHC. The MVA analysis, most sensitive for discovery, observes an excess of events at 125 GeV with a local significance of 3.2sigma. The mass of the observed boson is measured to be 125.4 +/- 0.5( stat.) +/- 0.6(syst.) GeV. For a Higgs boson mass hypothesis of 125 GeV, the best fit signal strength is 0.78+0.28-0.26 times the SM Higgs boson cross-section. An upper limit on its natural width is found to be 6.9 GeV/c2 at 95% confidence level.;We also present results from searches for an additional Higgs boson decaying into two photons, treating the observed resonance as a background process. Cases in which the additional state is SM-like, fermiophobic or gauge-phobic have been considered. In addition, we present a search targeted at discriminating between a single Higgs boson at 125 GeV and two very close-by ones.
Keywords/Search Tags:Boson, Higgs, Gev, Present
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