Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

TLDR

The CMS search examined five decay channels—γγ, ZZ, WW, ττ, and bb̄—using 7 and 8 TeV proton‑proton collision data. A 5.0σ excess near 125 GeV—consistent with a new boson—was observed in γγ and ZZ channels, with a measured mass of 125.3 ± 0.4 (stat) ± 0.5 (syst) GeV, and the expected significance for a SM Higgs of that mass is 5.8σ.

Abstract

Results are presented from searches for the standard model Higgs boson in proton-proton collisions at sqrt(s) = 7 and 8 TeV in the Compact Muon Solenoid experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.1 inverse femtobarns at 7 TeV and 5.3 inverse femtobarns at 8 TeV. The search is performed in five decay modes: gamma gamma, ZZ, WW, tau tau, and b b-bar. An excess of events is observed above the expected background, with a local significance of 5.0 standard deviations, at a mass near 125 GeV, signalling the production of a new particle. The expected significance for a standard model Higgs boson of that mass is 5.8 standard deviations. The excess is most significant in the two decay modes with the best mass resolution, gamma gamma and ZZ; a fit to these signals gives a mass of 125.3 +/- 0.4 (stat.) +/- 0.5 (syst.) GeV. The decay to two photons indicates that the new particle is a boson with spin different from one.