Challenges and plans in search for Higgs decays to Invisible particles via VBF production with the ATLAS detector in Run II

The total decay width of the Higgs has not yet been constrained precisely. This allows for a sizable branching fraction where the Higgs decays into invisible particles, such as dark matter particles. The signature of such events would be a Higgs boson associated with a large missing transverse energy. This talk will discuss in detail the search for invisible decays of the Higgs produced in the Vector Boson Fusion (VBF) production mode using the 36.1 fb-1 p-p collisions at 13 TeV with the ATLAS detector. It will include the analysis techniques, leading constraints on sensitivity and resulting limits on the invisible branching fraction. Also discussed will be what we learned from the challenges faced by this analysis and how we are using that information to plan for the analysis using full Run 2 data. An interpretation of the result in the context of Higgs portal dark matter models and projection of limits on different Higgs masses will also be presented.