EFFECT FROM THE GLUON-FUSION SIGNAL AND BACKGROUND INTERFERENCE FOR HIGGS DECAYING TO γγ ANALYSIS AT THE LHC

We calculate the destructive interference factors between the Higgs decay H -> gamma gamma produced in gluon-fusion and the Standard Model (SM) continuum gg -> gamma gamma process, as a function of the scattering angle in the center-of-mass frame of the final two photons. The interference factors are studied with the selections based on the acceptance criteria of the ATLAS and CMS H -> gamma gamma searches at the LHC. The result shows that the destructive interference is only at an order of 2.5% for the SM Higgs analysis at the LHC. The factors are almost the same for the same Higgs mass hypothesis but with different proton proton collisions at root s = 7 TeV, 8 TeV, 13 TeV and 14 TeV. The destructive interference is far below the present uncertainty on the total cross-section prediction of Higgs, which is about 15% used at the LHC. A destructive interference factor of -2.5% is suggested to be used in the H -> gamma gamma analysis at the LHC, due to the effect from the interference for this decay channel.