Searches for mono-jet and mono-photon events with missing transverse momentum with the ATLAS detector

Events composed of one high transverse energy jet or photon and large missing transverse momentum represent one of the simplest and most striking signatures that can be observed at a hadron collider. The Standard Model contribution to 'monojet' events is dominated by a Z decaying to a pair of neutrinos plus a recoiling jet. Several new physics models predict monojet and monophoton events. They can occur via production of a jet/photon in association with an invisible particle or via pair production of invisible particles recoiling against a hard radiative jet or photon. The talk presents results from searches for new physics in monojet and monophoton events performed by the ATLAS experiment at the LHC.