In this work, we consider the process $e^{+}+e^{-}\to b\overline{b}+{\cancel{E}}_T$, at the future electron-positron colliders such as the International Linear Collider and Compact Linear Collider, to look for the dark matter (DM) effect and identify its nature at two different center-of-mass energies $E_{\mathrm{c}.\mathrm{m}.}=500\mathrm{GeV}$ and 1 TeV. For this purpose, we take two extensions of the standard model, in which the DM could be a real scalar or a heavy right-handed neutrino (RHN) similar to many models motivated by neutrino mass. In the latter extension, the charged leptons are coupled to the RHNs via a lepton flavor violating interaction that involves a charged singlet scalar. After discussing different constraints, we define a set of kinematical cuts that suppress the background and generate different distributions that are useful in identifying the DM nature. The use of polarized beams (like the polarization $P(e^{-},e^{+})=[+0.8,-0.3]$ at the International Linear Collider) makes the signal detection easier and the DM identification more clear, where the statistical significance gets enhanced by twice (five times) for scalar (RHN) DM.

• Received 18 July 2017

DOI:https://doi.org/10.1103/PhysRevD.96.055029