Search for new phenomena in events with missing transverse momentum and a Higgs boson decaying to two photons in pp collisions at s√=13 TeV with the ATLAS detector

A search for new phenomena in events with large missing transverse momentum and a Higgs boson decaying to two photons is presented. The search uses $ 13.3 ~\mathrm{fb}^{-1}$ of proton-proton collision data collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the CERN Large Hadron Collider in 2015 and 2016. No excess over the background expectation is observed. Limits are set on the production rates of the following theoretical models: two simplified models where the Standard Model--dark matter interaction is mediated by a new vector particle emitting a Higgs boson and decaying, either directly or through an intermediate state, into two invisible particles, and an effective theory model where a heavy scalar decays into a Higgs boson and a pair of dark matter candidates.