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Search for the standard model Higgs boson in the decay channel H-> ZZ -> 4l in pp collisions

A search for a Higgs boson in the $H \rightarrow ZZ$ four- lepton decay channel, with each Z boson decaying to an electron or a muon is reported. The search covers Higgs boson mass hypotheses in the range $110 < m_H < 800 GeV$. The analysis uses pp collision data recorded by the CMS detector at the LHC, and corresponding to integrated luminosities of $5 fb^{; ; -1}; ; $ at at $\sqrt{; ; s}; ; $ = 7 TeV and $3 fb^{; ; -1}; ; $ at $\sqrt{; ; s}; ; $ = 8 TeV. The mass distributions measured with four-lepton invariant masses $m_{; ; 4\ell}; ; > 100 GeV$ is found globally consistent with the expectation of standard model background production of ZZ pairs. Upper limits at 95\% confidence level exclude the standard model Higgs boson in the range 130--520 GeV. An excess of events is observed in the mass range $120 < m_{; ; 4\ell}; ; < 130 GeV$ making the observed limits weaker than expected in the absence of a signal. These events cluster in a peak around a mass $ m_{; ; 4\ell}; ; \simeq 126 GeV$, giving rise to a local excess with respect to the background expectation, with a significance for the standard model Higgs boson hypothesis of $3.2\sigma$.

CMS; Higgs boson

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