Speaker
Dr
Jason Evans
(University of Minnesota/FTPI)
Description
Successful models of Pure Gravity Mediation (PGM) with radiative electroweak symmetry
breaking can be expressed with as few as two free parameters which can be taken as the
gravitino mass and tan β. These models easily support a 125-126 GeV Higgs mass at the
expense of a scalar spectrum in the multi-TeV range and a much lighter wino as the lightest
supersymmetric particle. In these models, it is also quite generic that the Higgs mixing mass
parameter, μ, which is determined by the minimization of the Higgs potential is also in the
multi-TeV range. For μ > 0, the thermal relic density of winos is too small to account for
the dark matter. The same is true for μ < 0 unless the gravitino mass is of order 500 TeV.
Here, we consider the origin of a multi-TeV μ parameter arising from the breakdown of a
Peccei-Quinn (PQ) symmetry. A coupling of the PQ-symmetry breaking field, P , to the
MSSM Higgs doublets, naturally leads to a value of μ ∼ P^2 /MP ∼ O(100) TeV and of
order that is required in PGM models. In this case, axions make up the dark matter or
some fraction of the dark matter with the remainder made up from thermal or non-thermal
winos. We also provide solutions to the problem of isocurvature fluctuations with axion dark
matter in this context.
Author
Dr
Jason Evans
(University of Minnesota/FTPI)
