Search for new phenomena in high-mass diphoton state with ATLAS at $\sqrt{s}$ =13 TeV

After the discovery of the Higgs boson, one of the most important task of high energy physics at the LHC is to look for signatures of new physics beyond the Standard Model (SM). In various extensions of the SM, new high mass states are decaying into two photons. Searches for such states in the ATLAS experiment at the LHC are described in this poster. The analysis is based on pp collisions data corresponding to an integrated luminosity of 36.7 fb-1 at $\sqrt{s}$ =13 TeV recorded in 2015 and 2016. Two different studies are performed, one targeted for the search of a spin-2 particle, using the Randall-Sundrum and the ADD extra-dimension model as benchmark models, and one optimized for the search of a spin-0 particle.