  A search for dark matter particles is performed using events with large
missing transverse momentum, at least one energetic jet, and no leptons, in
proton-proton collisions at sqrt(s) = 13 TeV collected with the CMS detector at
the LHC. The data sample corresponds to an integrated luminosity of 12.9
inverse femtobarns. The search includes events with jets from the hadronic
decays of a W or Z boson. The data are found to be in agreement with the
predicted background contributions from standard model processes. The results
are presented in terms of simplified models in which dark matter particles are
produced through interactions involving a vector, axial-vector, scalar, or
pseudoscalar mediator. Vector and axial-vector mediator particles with masses
up to 1.95 TeV, and scalar and pseudoscalar mediator particles with masses up
to 100 and 430 GeV respectively, are excluded at 95% confidence level. The
results are also interpreted in terms of the invisible decays of the Higgs
boson, yielding an observed (expected) 95% confidence level upper limit of 0.44
(0.56) on the corresponding branching fraction. The results of this search
provide the strongest constraints on the dark matter pair production cross
section through vector and axial-vector mediators at a particle collider. When
compared to the direct detection experiments, the limits obtained from this
search provide stronger constraints for dark matter masses less than 5, 9, and
550 GeV, assuming vector, scalar, and axial-vector mediators, respectively. The
search yields stronger constraints for dark matter masses less than 200 GeV,
assuming a pseudoscalar mediator, when compared to the indirect detection
results from Fermi-LAT.
