Study of the spin and parity of the Higgs boson in HVV decays with the ATLAS detector

In this paper, studies of the spin, parity and Lagrangian tensor structure of the Higgs boson in the \hZZ , \hWW\ and \hgg\ decay processes at the LHC are presented. The investigations are based on 25fb−1 of pp collision data collected by the ATLAS experiment at s√=7~\TeV\ and s√=8~\TeV. The Standard Model (SM) Higgs boson hypothesis, corresponding to the quantum numbers JP=0+, is tested against several alternative spin models. They include the non-SM spin-0 and the spin-2 model with universal and non-universal couplings to fermions and vector bosons. The analysed data allow to exclude all alternative models in favour of the SM Higgs boson hypothesis at more than 99.9%~confidence level. The tensor structure of the HVV interaction in the spin-0 hypothesis is also investigated using the \hZZ\ and \hWW\ decays. The observed distributions of the variables sensitive to the ratios of the non-SM tensor couplings to the SM ones, \KtildeH\ and \KtildeA, are compatible with the SM predicted values of zero. Assuming that the \KtildeH\ and \KtildeA\ couplings are the same for the HWW and HZZ processes, values of the BSM couplings outside the intervals −0.73<\KtildeH<0.63 and −2.18<\KtildeA<0.83 are excluded at 95\% ~confidence level.