Search for scalar Dark Energy with ATLAS

We present the first constraints from a search for light scalar particles produced in association with a pair of top quarks and jet final states using 36 fb$^{-1}$ of proton-proton collisions at 13 TeV collected using the ATLAS detector at the Large Hadron Collider at CERN. The results are interpreted in the context of an Effective Field Theory model of scalar Dark Energy with conformal and disformal couplings. The results provide the most stringent constraints on the scale of disformal interactions between Dark Energy and Standard Model matter, improving the constraints obtained from cosmological and solar system tests by several orders of magnitude.