Search for dark matter and compressed mass-spectra supersymmetry with the vector boson fusion topology in pp collisions at sqrt(s) = 8 TeV

The first search for dark matter candidate production through pure electroweak vector boson fusion processes is presented. Events with two jets in the vector boson fusion topology and large missing transverse momentum are analyzed using data from proton-proton collisions at $\sqrt{s} = 8$ TeV collected with the CMS detector. %corresponding to an integrated luminosity of $18.5 fb^{-1}$ In the context of supersymmetric models with a compressed mass spectrum, which may yield visible particles with momenta too low to detect efficiently, the vector boson fusion topology boosts the momentum imbalance from the escaping lightest supersymmetric particle (a dark matter candidate), providing a distinct signature to discriminate signal events from backgrounds. The dijet mass spectrum measured in data is observed to be compatible with the expected standard model prediction. Limits are set on the production cross section and mass of fermionic dark matter particles in the context of an effective field theory with a heavy mediator, as well as pairs of scalar bottom quarks that are nearly mass degenerate with the lightest supersymmetric particle.