  A search for the production of single-top-quarks in association with missing
energy performed in proton-proton collisions at a centre-of-mass energy of
$\sqrt{s}=8$ TeV with the ATLAS experiment is presented. No deviation from the
Standard Model prediction is observed, and upper limits are set on the
production cross-section for resonant and non-resonant production of an
invisible exotic state in association with a right-handed top quark.
