Measurements of Higgs boson properties in the diphoton decay channel in proton-proton collisions at $$ \sqrt{s}=13 $$ TeV

Abstract

Measurements of Higgs boson properties in the H → γγ decay channel are reported. The analysis is based on data collected by the CMS experiment in protonproton collisions at √ s = 13 TeV during the 2016 LHC running period, corresponding to an integrated luminosity of 35.9 fb −1 . Allowing the Higgs mass to float, the measurement yields a signal strength relative to the standard model prediction of 1.18 +0.17 −0.14 = 1.18 +0.12 −0.11 (stat) +0.09 −0.07 (syst) +0.07 −0.06 (theo), which is largely insensitive to the exact Higgs mass around 125 GeV. Signal strengths associated with the different Higgs boson production mechanisms, couplings to bosons and fermions, and effective couplings to photons and gluons are also measured.

Search for a standard model-like Higgs boson in the mass range between 70 and 110 GeV in the diphoton final state in proton-proton collisions at s=8 and 13 TeV

“…The same photon reconstruction is used as in [40] ( [41]) for the 8 (13) TeV data. For the 8 TeV data, photon candidates are reconstructed from energy deposits in the ECAL grouped into extended clusters or groups of clusters known as "superclusters".…”

“…The preselection is designed to be slightly more stringent than the trigger requirements. A photon identification BDT combining lateral shower shape variables, isolation variables, the median energy density, the pseudorapidity, and the raw energy is used to separate prompt photons from nonprompt photons resulting from neutral meson decays [40,41]. Each photon candidate must satisfy the preselection requirements as well as a requirement on the minimum value of the photon identification BDT output.…”

“…Each photon candidate must satisfy the preselection requirements as well as a requirement on the minimum value of the photon identification BDT output. As in [40,41], the efficiencies of the minimum photon identification BDT output requirement and preselection criteria (except for the electron veto requirement) are measured with a tag-andprobe technique using Z → e + e − events. The fraction of photons that satisfy the electron veto requirement is measured with Z → µ + µ − γ events, in which the photon is produced by finalstate radiation providing a sample of prompt photons with purity higher than 99%.…”

“…The simulated SM Higgs boson events are used to construct a parameterized signal model that is defined continuously for any value of Higgs boson mass between 80 (70) and 110 GeV, for the 8 (13) TeV data. The photon energy resolution predicted by the simulation is modified by a Gaussian smearing determined from the comparison between the Z → e + e − line-shape in data and simulation, where the electron energies have been corrected with factors developed for photons, using the same procedure as that described in [40,41]. The amount of smearing is extracted differen-tially in bins of |η| and the R 9 shower shape variable [43], defined as the energy sum of 3×3 crystals centered on the most energetic crystal in the ECAL cluster divided by the energy of the cluster.…”

“…In this analysis, as in [11,40,41], the background is modeled by fitting analytic functions to the observed diphoton mass distributions, in each of the event classes. The fits are performed over the range 75 (65) < m γγ < 120 GeV for the 8 (13) TeV data.…”