  A search for dark matter produced in association with a top quark pair is
presented. The search is performed using 19.7 $\mathrm{fb^{-1}}$ of
proton-proton collisions recorded at a center of mass energy of 8 TeV with the
CMS detector at the LHC. The signature investigated is top quark pairs in the
semi-leptonic final state plus missing transverse energy. This work focuses in
particular on dark matter production through scalar interaction where a
proportionality to the quark mass is expected.

High Energy Physics - Experiment;High Energy Physics - Phenomenology