Dark Matter from Lorentz Invariance and the LHC

In extra dimensional models, a Dark Matter candidate can be present thanks to a Kaluza-Klein parity which makes the lightest resonances stable. However, compactifications considered sofar need the symmetry to be imposed by hand on the model: here we propose the unique orbifold in 6 dimensions where such parity arises naturally as part of the unbroken 6D Lorentz invariance. As an example we introduce a model of universal extra dimensions where all standard model fields propagate in the extra dimensions. The dark matter candidate is a scalar photon and its preferred mass range lies below 300 GeV. Due to the small splitting between states in the same Kaluza-Klein tier, discovery of the lightest tiers is challenging at the LHC.