Living orthogonally: quasi-universal extra dimensions

The minimal Universal Extra Dimension scenario is no longer viable owing to opposing constraints from the observed relic density on the one hand, and the non-observation of new states at the LHC on the other. Simple extensions in five-dimensions can only postpone the inevitable. Here, we propose a six-dimensional alternative with the key feature being that the SM quarks and leptons are localized on orthogonal directions whereas gauge bosons traverse the entire bulk. This is not only consistent with all the current constraints opposing the minimal Universal Extra Dimension scenario but also allows for a multi-TeV dark matter particle without the need for any fine-tuning. In addition, it promises a plethora of new signatures at the LHC and other future experiments.