Electroweak and dark matter constraints on a [formula omitted] in models with a hidden valley

Abstract

We consider current precision electroweak data, Z ′ searches and dark matter constraints and analyse their implications for an extension of the Standard Model (SM) that includes an extra U ( 1 ) ′ massive gauge boson and a particular hidden sector (“hidden valley”) with a confining (QCD-like) gauge group. The constraints on the Z ′ with arbitrary Z – Z ′ kinetic mixing coming from direct searches and precision tests of the Standard Model are analysed and shown to lead to a lower limit of 800 GeV on its mass. Renormalisable interactions involving the Z ′ probe the physics of the hidden valley sector which contains a pseudoscalar dark matter candidate. We find that dark matter constraints place an upper bound on the mass of the Z ′ of O ( 10 ) TeV . A TeV mass scale is needed for the hidden valley states, and the Sommerfeld factor for p-wave dark matter annihilation is found significantly to suppress the allowed parameter space of the model.