Search for dark matter in association with a top quark pair at $\sqrt{s}=13~\mathrm{TeV}$ in the dilepton channel

A search is performed for dark matter production with top quark pairs decaying to dileptons in proton-proton collisions at centre of mass energy $13~\mathrm{TeV}$. Results are interpreted using simplified models for collider production of dark matter and constraints are placed on the parameter space. The data corresponds to an integrated luminosity of $2.2~\mathrm{fb}^{-1}$ collected by the CMS detector at the LHC in 2015. A combination is performed with previously reported analyses in the semileptonic and hadronic channels.