Search for a new resonance in the WZ leptonic decay channel in proton-proton collisions using the ATLAS detector

Although, the Standard Model of particle physics (SM) is currently the best model we have to describe the fundamental particles of the universe, it still has limitations. Some of the known limitations of the SM are in the description of neutrinos, dark matter, the low mass of the Higgs boson which leads to hierarchy and naturalness problems, among others. Therefore, there is a need for physics beyond SM. A simple way to discover new physics and particles are resonance searches. The search for a resonance decaying into dibosons is a powerful probe for electroweak symmetry breaking, one of the predictions at the hearth of the SM. A search for a heavy resonance decaying into WZ in the fully leptonic channel (electrons and muons) is performed in this work using the proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 139 $fb^{-1}$. This search fits the LHC objectives as this search is most sensitive at low masses and complements the searches performed in hadronic channels. Limits on the production cross-section times branching ratio are obtained as a function of the resonance mass for resonances arising from two different models, the Heavy Vector Triplet and Georgi-Machacek model. Two different production modes are considered, the vector boson fusion and the Drell-Yan, on which independent limits are set.