Little solution to the little hierarchy problem: A vectorlike generation

Abstract

We present a simple solution to the little hierarchy problem in the minimal supersymmetric standard model: a vectorlike fourth generation. With $\mathcal{O}(1)$ Yukawa couplings for the new quarks, the Higgs mass can naturally be above 114 GeV. Unlike a chiral fourth generation, a vectorlike generation can solve the little hierarchy problem while remaining consistent with precision electroweak and direct production constraints, and maintaining the success of the grand unified framework. The new quarks are predicted to lie between $\ensuremath{\sim}300--600\text{ }\text{ }\mathrm{GeV}$ and will thus be discovered or ruled out at the LHC. This scenario suggests exploration of several novel collider signatures.