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Abstract |
The observed abundance of dark matter can be explained by a thermal relic that annihilates
with a weak scale cross section. This so-called “WIMP miracle” points to dark matter masses
near the TeV scale. However, dramatic improvements in the sensitivity of direct detection
experiments targeting TeV scale dark matter, and the lack of a discovery so far, motivates
exploration beyond the WIMP. I will review three well-known “exceptions” to the WIMP miracle
argument: (1) annihilations near a pole, (2) annihilations among multiple channels
(“coannihilations”), and (3) annihilations into heavier states (“forbidden channels”). I will argue
that forbidden channels and coannihilations are both mechanisms for producing dark matter
that is exponentially lighter than the weak scale. I will also introduce a fourth exception,
“coscattering,” where the dark matter abundance is produced by inelastic scattering against
the thermal bath, instead of annihilations. |
