Speaker
Description
WIMP particles down to MeV-scale masses can be thermal relic dark matter candidates, provided they fulfill two requirements. These dictate what kind of models can realise them.
First, to have a sufficiently large annihilation rate in the early Universe, a new light mediator particle coupled to the light SM degrees of freedom is necessary. Due to the chiral structure of the SM, the number of mediator candidates is limited. This talk will place some emphasis on the possibility of a light scalar from a second Higgs doublet.
Second, the present day annihilation into visible particles is such a sensitive probe that it needs to be suppressed compared to the early Universe. In the case of kinematically forbidden annihilations into charged fermions, loop-level annihilation into gamma rays emerges as an informative probe. Coupling to neutrinos instead could still result in observable signals at neutrino experiments due to the large annihilation rate of sub-GeV thermal relic DM.
