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  • Study of the spin and parity of the Higgs boson in diboson decays with the ATLAS detector
    Publication . ATLAS collaboration (2842 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Cantrill, Robert; Carvalho, João; Castro, Nuno Filipe; Conde Muiño, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gonçalo, Ricardo; Jorge, Pedro; Lopes, Lourenco; Machado Miguens, Joana; Maio, Amélia; Maneira, José; Onofre, António; Palma, Alberto; Pedro, Rute; Pina, João Antonio; Pinto, Belmiro; Santos, Helena; Saraiva, João; Silva, José; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, Helmut
    Studies of the spin, parity and tensor couplings of the Higgs boson in the $H \rightarrow ZZ^{*} \rightarrow 4 \ell $ , $H \rightarrow WW^{*} \rightarrow e \nu \mu \nu $ and $H \rightarrow \gamma \gamma $ decay processes at the LHC are presented. The investigations are based on $25\,\mathrm{fb}^{-1}$ of pp collision data collected by the ATLAS experiment at $\sqrt{s}=7$  TeV and $\sqrt{s}=8$  TeV. The Standard Model (SM) Higgs boson hypothesis, corresponding to the quantum numbers $J^{P}=0^{+}$ , is tested against several alternative spin scenarios, including non-SM spin-0 and spin-2 models with universal and non-universal couplings to fermions and vector bosons. All tested alternative models are excluded in favour of the SM Higgs boson hypothesis at more than 99.9 % confidence level. Using the $H \rightarrow ZZ^{*} \rightarrow 4 \ell $ and $H \rightarrow WW^{*} \rightarrow e \nu \mu \nu $ decays, the tensor structure of the interaction between the spin-0 boson and the SM vector bosons is also investigated. The observed distributions of variables sensitive to the non-SM tensor couplings are compatible with the SM predictions and constraints on the non-SM couplings are derived.
    2015-10-06Journal article Open access Show more
  • (D)Estratégia de Uma Fusão
    Publication . Dias, Lígia Duarte Pereira; Fonseca, José Manuel da
    2015-10-06Master thesis Restricted access Show more
  • Search for photonic signatures of gauge-mediated supersymmetry in 8 TeV pp collisions with the ATLAS detector
    Publication . ATLAS collaboration (2855 authors); Aguilar-Saavedra, Juan Antonio; Amor Dos Santos, Susana Patricia; Anjos, Nuno; Araque, Juan Pedro; Cantrill, Robert; Carvalho, João; Castro, Nuno Filipe; Conde Muiño, Patricia; Da Cunha Sargedas De Sousa, Mario Jose; Fiolhais, Miguel; Galhardo, Bruno; Gomes, Agostinho; Gonçalo, Ricardo; Jorge, Pedro; Lopes, Lourenco; Machado Miguens, Joana; Maio, Amélia; Maneira, José; Onofre, António; Palma, Alberto; Pedro, Rute; Pina, João Antonio; Santos, Helena; Saraiva, João; Silva, José; Tavares Delgado, Ademar; Veloso, Filipe; Wolters, Helmut
    A search is presented for photonic signatures motivated by generalized models of gauge-mediated supersymmetry breaking. This search makes use of 20.3  fb-1 of proton-proton collision data at s=8  TeV recorded by the ATLAS detector at the LHC, and explores models dominated by both strong and electroweak production of supersymmetric partner states. Four experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon, lepton, b-quark jet, or jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction and model-dependent 95% confidence-level exclusion limits are set.
    2015-10-06Journal article Open access Show more