A Dark Matter Candidate from an Extra (Non-Universal) Dimension

We show that a recently constructed five–dimensional (5D) model with gauge– Higgs unification and explicit Lorentz symmetry breaking in the bulk, provides a natural dark matter candidate. This is the lightest Kaluza–Klein particle odd under a certain discrete Z2 symmetry, which has been introduced to improve the naturalness of the model, and resembles KK–parity but is less constraining. The dark matter candidate is the first KK mode of a 5D gauge field and electroweak bounds force its mass above the TeV scale. Its pair annihilation rate is too small to guarantee the correct relic abundance; however coannihilations with colored particles greatly enhance the effective annihilation rate, leading to realistic relic densities.