Probing Dark Matter-electron interactions in the Cosmic Microwave Background Radiation

In this article, we consider Dark Matter (DM) interactions and study the same in the light of the Cosmic Microwave Background Radiation (CMBR) data. In particular, we focus on the DM-electron interactions. Assuming that such interactions are mediated by rather heavy mediators, we consider effective operators describing the relevant interaction terms in the lagrangian. The presence of such interaction terms leads to both DM annihilation and DM-electron scattering (drag). We focus on operators which lead to velocity-independent DM annihilation and DM-electron scattering cross-sections. Using the CMBR data, we study the implications of both of these effects imposing constraints on the respective effective operators. This analysis underscores the importance of taking both scattering and annihilation processes into consideration in the study of DM interactions. We observe that the constraints on the DM annihilation and scattering cross-sections can change, up to about 13% and 12%, respectively, for the benchmark scenarios we considered, depending on the mass of DM, as compared to the scenario where only DM annihilation is accounted for.