  A search for dark matter particles directly produced in proton-proton
collisions recorded by the CMS experiment at the LHC is presented. The data
correspond to an integrated luminosity of 18.8 inverse femtobarns, at a
center-of-mass energy of 8 TeV. The event selection requires at least two jets
and no isolated leptons. The razor variables are used to quantify the
transverse momentum balance in the jet momenta. The study is performed
separately for events with and without jets originating from b quarks. The
observed yields are consistent with the expected backgrounds and, depending on
the nature of the production mechanism, dark matter production at the LHC is
excluded at 90% confidence level for a mediator mass scale Lambda below 1 TeV.
The use of razor variables yields results that complement those previously
published.
