• ATLAS
• diboson
• graviton
• heavy vector triplet
• resonances
• semileptonic

With the discovery of the Higgs boson by the ATLAS and CMS experiments
at the LHC at CERN in 2012, the Standard Model is now complete, yet
unanswered questions are still present. In example the Standard Model
does not explain the hierarchy between the weak and Planck scales, nor
it includes a dark matter candidate, nor it explain the origin of barion
asymmetry. For this reason, one of the goals of particle physics
research is to find new hints of physics beyond the Standard Model that
could answer some of these questions. Analyses searching for di-boson
resonances are a very powerful tool to investigate many beyond the
Standard Model scenarios such as extension of the Higgs sector, Heavy
Vector triplets (W' and Z' ) or excited states of Gravitons. These
searches exploit many decay channels of the two bosons allowing to
select topologies with varied signal to background ratios and
statistics. This thesis describes the search for new resonances decaying
to a pair of massive vector bosons (X → WW, W Z) in a 36.1 fb −1 data
sample of proton-proton collisions produced at a centre-of-mass energy
of √s = 13TeV collected with the ATLAS detector. The final state is
reconstructed through the semi-leptonic decays lνqq (l = e, μ) of the
two vector bosons.