Forbidden Dark Matter at the Weak Scale via the Top Portal

Understand

At the tail of its velocity distribution, cold dark matter (DM) can annihilate at finite temperature to states heavier than itself.

• We explore the possibility that DM freezeout is dictated by these "forbidden annihilations" at the electroweak scale.
• Demanding that annihilation products be Standard Model particles, we find that for the forbidden mechanism to primarily set the DM relic abundance, DM must couple predominantly, if not solely, to top quarks.
• This can be arranged by invoking a non-trivial flavor structure such as Minimal Flavor Violation.