INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at √s = 7 and 8 TeV in the ATLAS experiment
ATLAS COLLABORATION, G. AAD, M.T. DOVA ET AL
Workshop; 50th Rencontres de Moriond on Electroweak Interactions and Unified Theories,; 2015
Combined analyses of the Higgs boson production and decay rates as well as of its coupling strengths to vector bosons and fermions are presented. Included in the combinations are the results of the decay modes H → γγ, ZZ∗, WW∗, Zγ, bb ̄, ττ and μμ, and the constraints on the associated production with a pair of top quarks and on the off-shell coupling strengths of the Higgs boson. The results are based on the LHC proton-proton collision datasets, with integrated luminosities of up to 4.7 fb−1 at √s = 7 TeV and 20.3 fb−1 at √s = 8 ￼￼TeV, recorded by the ATLAS detector in 2011 and 2012. Combining all production modes and decay channels, the measured signal yield, normalised to the Standard Model expectation, is 1.18 ± 0.10 ± 0.07±0.08, where the first error reflects the statistical uncertainty and 0.07 the second and third errors reflect respectively the experimental and theoretical systematic uncertainties. Strong evidence is found for the vector boson fusion process with a signific- ance of 4.3σ. The observed Higgs boson production and decay rates are interpreted in a leading order coupling framework, exploring a wide range of benchmark coupling models both with and without assumptions on the Higgs boson width and assumption on the SM particle content in loop processes. Within the assumption of unified couplings to up-type fermions, down-type fermions and the W/Z boson respectively, strong evidence for Higgs boson couplings to down-type fermions is found with a significance of 4.5σ. Generic Higgs boson coupling models that allow to measure coupling strengths to μ, τ leptons, b, t quarks and W , Z bosons, or ratios of these coupling strengths, are presented. The observed data are found to be compatible with the SM expectations for a Higgs boson at a mass of 125.36 GeV for all models considered.