Discovery of the Higgs Boson Decaying to Two Photons

The Standard Model (SM) of particle physics fundamentally relies on the existence of the Higgs boson. This massive particle is a relic of the underlying and hidden Higgs field, whose transformation into the Higgs boson provides mass to weak bosons and all massive fermions in the SM. This particle has been long-sought and finally using data from proton-proton collisions at the LHC, CMS and ATLAS experiments have discovered a particle which is compatible with the SM Higgs boson. Presented here is the development of one of the discovery channels, $\mathrm{H}\rightarrow\gamma\gamma$, and the final $\mathrm{H}\rightarrow\gamma\gamma$ analysis and results using the full luminosity of the LHC Run 1 dataset $\sim$25 $\mathrm{fb}^{-1}$ at 7 or 8 TeV center of mass energy. The observed (expected) significance of this di-photon excess in the final analysis is $5.7\sigma$ ($5.2\sigma$) with a measured signal strength of $\sigma / \sigma_{SM} = 1.14^{+0.26}_{-0.23}$. The mass of this Higgs boson is not predicted by the SM. Using the $\mathrm{H}\rightarrow\gamma\gamma$ channel, $\mathrm{M}_{\text{H}}$ is measured to be $124.70^{+0.35}_{-0.34}$ GeV. Other measured quantities are presented including the signal strength modifiers of different production mechanisms and spin hypothesis tests between spin-0 and spin-2 models. Searches for this Higgs boson decaying to the di-muon and di-electron states are presented. No excess is observed and universal lepton decays of this particle are therefore ruled out, supporting the SM Higgs boson interpretation. In addition, relevant searches, observations and measurements from CMS that characterize this particle are presented.