  Results are presented from a search for particle dark matter (DM), extra
dimensions, and unparticles using events containing a jet and an imbalance in
transverse momentum. The data were collected by the CMS detector in
proton-proton collisions at the LHC and correspond to an integrated luminosity
of 19.7 inverse femtobarns at a centre-of-mass energy of 8 TeV. The number of
observed events is found to be consistent with the standard model prediction.
Limits are placed on the DM-nucleon scattering cross section as a function of
the DM particle mass for spin-dependent and spin-independent interactions.
Limits are also placed on the scale parameter M[D] in the ADD model of large
extra dimensions, and on the unparticle model parameter Lambda[U]. The
constraints on ADD models and unparticles are the most stringent limits in this
channel and those on the DM-nucleon scattering cross section are an improvement
over previous collider results.
