MSSM4G: Reviving Bino Dark Matter with Vector-like 4th Generation
  Particles
  We supplement the minimal supersymmetric standard model (MSSM) with
vector-like copies of standard model particles. Such 4th generation particles
can raise the Higgs boson mass to the observed value without requiring very
heavy superpartners, improving naturalness and the prospects for discovering
supersymmetry at the LHC. Here we show that these new particles are also
motivated cosmologically: in the MSSM, pure Bino dark matter typically
overcloses the Universe, but 4th generation particles open up new annihilation
channels, allowing Binos to have the correct thermal relic density without
resonances or co-annihilation. We show that this can be done in a sizable
region of parameter space while preserving gauge coupling unification and
satisfying constraints from collider, Higgs, precision electroweak, and flavor
physics.
