Search for the Standard Model Higgs in H → ZZ → 4l channel with the CMS experiment

Abstract

Results of the experimental search for the Standard Model Higgs in the H → ZZ → 4l (with l=e,μ) decay channel at collision energies of 7 and 8 TeV at the LHC are presented. The analysis uses pp collision data recorded by the CMS detector at the LHC, corresponding to integrated luminosities of 5.05 fb−1 at collision energy of 7 TeV and 12.2 fb−1 at 8 TeV. A complete description of the H → ZZ → 4l analysis is provided by inspecting the most important aspects such as the lepton identification and isolation, the kinematics, the selection steps and the background control from data. The existence of the Higgs boson would be statistically revealed by the presence of a resonance peak in the four-lepton invariant mass distribution. The search covers the overall Higgs boson mass hypotheses in the range 110 < mH < 1000 GeV/c2 and a statistical interpretation of the results in that range is provided. The existence of the Standard Model Higgs boson has been excluded in a wide region of mass at 95% of confidence level, while a 4.5σ excess has been observed around a mass of 126 GeV/c2. A measurement of the mass of the new boson discovered gives 126.2 ±0.6(stat)±0.2(syst) GeV/c2. The hypothesis 0+ of the standard model for the spin J=0 and parity P=+1 quantum numbers is found to be consistent with the observation.