OBSERVATION AND MEASUREMENT OF THE HIGGS-LIKE BOSON AT 125 GEV IN THE TWO-PHOTON DECAY CHANNEL WITH THE CMS EXPERIMENT

Abstract

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 3.2 sigma. 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/c^2 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.