  A search has been made for events containing an energetic jet and an
imbalance in transverse momentum using a data sample of pp collisions at a
center-of-mass energy of 7 TeV. This signature is common to both dark matter
and extra dimensions models. The data were collected by the CMS detector at the
LHC and correspond to an integrated luminosity of 5.0 inverse femtobarns. The
number of observed events is consistent with the standard model expectation.
Constraints on the dark matter-nucleon scattering cross sections are determined
for both spin-independent and spin-dependent interaction models. For the
spin-independent model, these are the most constraining limits for a dark
matter particle with mass below 3.5 GeV, a region unexplored by direct
detection experiments. For the spin-dependent model, these are the most
stringent constraints over the 0.1-200 GeV mass range. The constraints on the
Arkani-Hamed, Dimopoulos, and Dvali model parameter MD determined as a function
of the number of extra dimensions are also an improvement over the previous
results.
