Symmetric tensor portals to dark matter I: Creation of dark scalars

We examine the creation of scalar dark matter through a symmetric tensor portal. We find that both freeze-in and thermal freeze-out through a symmetric tensor mediator can create scalar dark matter. The required tensor masses for freeze-in are much larger than for freeze-out for the same dark-matter mass, in agreement with the nonthermalization assumption in freeze-in scenarios. • A symmetric tensor portal can account for scalar dark matter both through freeze-in and through freeze-out of dark matter. • For fixed tensor mass, freeze-in predicts much smaller dark matter masses than freeze-out. • The larger mediator mass for given dark matter mass in freeze-in (as compared to freeze-out) complies with the assumption of nonthermalization in freeze-in.