Search for a Higgs boson decaying into a Z and a photon in pp collisions at √s=7 and 8 TeV

Abstract

A search for a Higgs boson decaying into a Z boson and a photon is described. The analysis is performed using proton–proton collision datasets recorded by the CMS detector at the LHC. Events were collected at center-of-mass energies of 7 TeV and 8 TeV, corresponding to integrated luminosities of 5.0 fb−1 and 19.6 fb−1, respectively. The selected events are required to have opposite-sign electron or muon pairs. No excess above standard model predictions has been found in the 120–160 GeV mass range and the first limits on the Higgs boson production cross section times the H→ZγH→Zγ branching fraction at the LHC have been derived. The observed at 95% confidence level limits are between about 4 and 25 times the standard model cross section times the branching fraction. For a standard model Higgs boson mass of 125 GeV the expected limit at the 95% confidence level is 10 and the observed limit is 9.5. Models predicting the Higgs boson production cross section times the H→Zγ branching fraction to be larger than one order of magnitude of the standard model prediction are excluded for most of the 125–157 GeV mass range.