Heavy Bino Dark Matter and Collider Signals in the MSSM with Vector-like
  4th-Generation Particles
  MSSM4G models, in which the minimal supersymmetric standard model is extended
to include vector-like copies of standard model particles, are promising
possibilities for weak-scale supersymmetry. In particular, two models, called
QUE and QDEE, realize the major virtues of supersymmetry (naturalness
consistent with the 125 GeV Higgs boson, gauge coupling unification, and
thermal relic neutralino dark matter) without the need for fine-tuned relations
between particle masses. We determine the implications of these models for dark
matter and collider searches. The QUE and QDEE models revive the possibility of
heavy Bino dark matter with mass in the range 300-700 GeV, which is not usually
considered. Dark matter direct detection cross sections are typically below
current limits, but are naturally expected above the neutrino floor and may be
seen at next-generation experiments. Indirect detection prospects are bright at
the Cherenkov Telescope Array, provided the 4th-generation leptons have mass
above 350 GeV or decay to taus. In a completely complementary way, discovery
prospects at the LHC are dim if the 4th-generation leptons are heavy or decay
to taus, but are bright for 4th-generation leptons with masses below 350 GeV
that decay either to electrons or to muons. We conclude that the combined set
of direct detection, CTA, and LHC experiments will discover or exclude these
MSSM4G models in the coming few years, assuming the Milky Way has an Einasto
dark matter profile.
