  Several new physics scenarios can lead to monojet signatures at the LHC. If
such events are observed above the Standard Model background it will be
important to identify their origin. In this paper we compare and contrast these
signatures as produced in two very different pictures: vector or scalar
unparticle production in the scale-invariant/conformal regime and graviton
emission in the Arkani-Hamed, Dimopoulos and Dvali extra-dimensional model. We
demonstrate that these two scenarios can be distinguished at the LHC for a
reasonable range of model parameters through the shape of their respective
monojet and/or missing $E_T$ distributions.
