Search for the decay of a Higgs boson in the ℓℓγ channel in proton-proton collisions at √s=13 TeV

Abstract

A search for a Higgs boson decaying into a pair of electrons or muons and a photon is described. Higgs boson decays to a Z boson and a photon (H → Zγ → ``γ,` = e or µ), or to two photons, one of which has an internal conversion into a muon pair (H → γ∗γ → µµγ) were considered. The analysis is performed using a data set recorded by the CMS experiment at the LHC from proton-proton collisions at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 35.9fb−1. No significant excess above the background prediction has been found. Limits are set on the cross section for a standard model Higgs boson decaying to opposite-sign electron or muon pairs and a photon. The observed limits on cross section times the corresponding branching fractions vary between 1.4 and 4.0 (6.1 and 11.4) times the standard model cross section for H → γ∗γ → µµγ (H → Zγ → ``γ) in the 120–130GeV mass range of the ``γ system. The H → γ∗γ → µµγ and H → Zγ → ``γ analyses are combined for mH = 125GeV, obtaining an observed (expected) 95% confidence level upper limit of 3.9(2.0) times the standard model cross section.