  A search for new phenomena is performed in final states containing one or
more jets and an imbalance in transverse momentum in pp collisions at a
centre-of-mass energy of 13 TeV. The analysed data sample, recorded with the
CMS detector at the CERN LHC, corresponds to an integrated luminosity of 2.3
inverse femtobarns. Several kinematic variables are employed to suppress the
dominant background, multijet production, as well as to discriminate between
other standard model and new physics processes. The search provides sensitivity
to a broad range of new-physics models that yield a stable weakly interacting
massive particle. The number of observed candidate events is found to agree
with the expected contributions from standard model processes, and the result
is interpreted in the mass parameter space of fourteen simplified
supersymmetric models that assume the pair production of gluinos or squarks and
a range of decay modes. For models that assume gluino pair production, masses
up to 1575 and 975 GeV are excluded for gluinos and neutralinos, respectively.
For models involving the pair production of top squarks and compressed mass
spectra, top squark masses up to 400 GeV are excluded.
