A search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ℓℓγ). The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120<150 GeV, and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H→γ*γ→ℓℓγ, where the dilepton invariant mass is less than 20 GeV. For a Higgs boson with mH=125 GeV, a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 (5.9-1.8+2.8) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H→(J/ψ)γ for the 125 GeV Higgs boson is set at 1.5×10-3.

Search for a Higgs boson decaying into γ*γ→ℓℓγ with low dilepton mass in pp collisions at √s=8 TeV

Bortignon P.;
2016-01-01

Abstract

A search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ℓℓγ). The analysis is performed using proton-proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120<150 GeV, and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H→γ*γ→ℓℓγ, where the dilepton invariant mass is less than 20 GeV. For a Higgs boson with mH=125 GeV, a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 (5.9-1.8+2.8) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H→(J/ψ)γ for the 125 GeV Higgs boson is set at 1.5×10-3.
2016
CMS; Dalitz decay; Higgs boson; Physics
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/289273
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