A bstract In this paper we present a realization of the dark dimension. We consider the 5D Standard Model coupling to gravity with one dimension compactified on an orbifold, which is seen as the dark dimension of size R. We stabilize the radion by Casimir effect wrapping around the compact dimension and recover the neutrino mass and 4D cosmological constant with the observed value. Orbifold can lead to a natural resolution of chirality problem in 5D at low energy, which we briefly discussed in the paper. Although we found that the radion mass is too light to survive under solar system tests of GR, several screening mechanisms might give us a solution, for example, the Chameleon mechanism.
Cui et al. (2026) studied this question.