Measurement of the properties of the new particle observed within the search for the Standard Model Higgs Boson in the H->ZZ(*)->4l decay channel at ATLAS

The discovery of a new particle within the search for the Standard Model Higgs boson in the H->ZZ->4l channel at ATLAS, with about 25/fb of data collected in pp collisions at the LHC, is discussed. Different hypotheses on the quantum numbers of the new boson are tested, by means of spin-parity studies based on a matrix element description of the H->ZZ decay amplitude. Prospects for the measurement of the tensor structure of the HZZ vertex in the spin zero hypothesis at a high--luminosity LHC are also presented.