Speaker: Aoife Bharucha (CNRS/CPT-Marseille)

When/Where: 4:30 PM, August 8, 2018 (Sala F-210)

Abstract: I wil discuss two models where the Dark Matter candidate is
a mixed fermion. First the MSSM, where the relic density of TeV-scale
wino-like neutralino dark matter is subject to potentially large
corrections as a result of the Sommerfeld effect. A recently
developed framework enables us to calculate the
Sommerfeld-enhanced relic density in general MSSM scenarios. Using
this framework, we perform a thorough study of the regions of
parameter space surrounding the well known pure-wino scenario: namely
the effect of sfermion masses being non-decoupled and of allowing
non-negligible Higgsino or bino components in the lightest neutralino.
The results reveal a number of phenomenologically interesting but so
far unexplored regions where the Sommerfeld effect is sizeable. I
will present these results, and revisit the bounds from Indirect
Detection on wino-like dark matter.
I will then discuss a more economical model of WIMP dark matter in
which the dark sector consists of the dark matter candidate, a
fermionic singlet, and its coannhihilation partner, a fermionic SU(2)
n-plet with n>=3. The dark sector is coupled to the SM Higgs boson via
non-renormalizable interactions. I will show how the viable parameter
space of this model can be mapped, taking into accounts constraints
from direct detection and collider experiments. In particular, the
near-degeneracy between the n-plet-like states naturally leads to
long-lived particles and hence to interesting signatures at the LHC.