Evidence for the spin-0 nature of the Higgs boson using ATLAS data

• Autor(a) principal: ATLAS collaboration (2923 authors)
• Data de Publicação: 2013
• Outros Autores: Aguilar-Saavedra, Juan Antonio, Amor Dos Santos, Susana Patricia, Anjos, Nuno, Cantrill, Robert, Carvalho, João, Castro, Nuno Filipe, Conde Muiño, Patricia, Da Cunha Sargedas De Sousa, Mario Jose, Do Valle Wemans, André, Fiolhais, Miguel, Galhardo, Bruno, Gomes, Agostinho, Gonçalo, Ricardo, Jorge, Pedro, Lopes, Lourenco, Machado Miguens, Joana, Maio, Amélia, Maneira, José, Marques, Carlos, Oliveira, Miguel Alfonso, Onofre, António, Palma, Alberto, Pina, João Antonio, Pinto, Belmiro, Santos, Helena, Saraiva, João, Silva, José, Tavares Delgado, Ademar, Veloso, Filipe, Wolters, Helmut
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.26/26445

Studies of the spin and parity quantum numbers of the Higgs boson are presented, based on proton-proton collision data collected by the ATLAS experiment at the LHC. The Standard Model spin-parity $J^P = 0^+$ hypothesis is compared with alternative hypotheses using the Higgs boson decays $H \to \gamma\gamma, H \to ZZ^* \to 4$ leptons and $H \to WW^* \to l\nu l\nu$, as well as the combination of these channels. The analysed dataset corresponds to an integrated luminosity of 20.7 fb$^{-1}$ collected at a centre-of-mass energy of $\sqrt{s}$ = 8 TeV. For the $H \to ZZ^* \to 4$-lepton decay mode the dataset corresponding to an integrated luminosity of 4.6 fb$^{-1}$ collected at $\sqrt{s}$ = 7 TeV is added. The data are compatible with the Standard Model $J^P = 0^+$ quantum numbers for the Higgs boson, whereas all alternative hypotheses studied in this letter, namely some specific $J^P = 0^-, 1^+, 1^-, 2^+$ models, are excluded at confidence levels above 97.8%. This exclusion holds independently of the assumptions on the coupling strengths to the Standard Model particles and in the case of the $J^P = 2^+$ model, of the relative fractions of gluon-fusion and quark-antiquark production of the spin-2 particle. The data thus provide evidence for the spin-0 nature of the Higgs boson, with positive parity being strongly preferred.