Implications of quantum gravity for dark matter in the brane-world scenario

TL;DR

This paper explores how quantum gravity constraints challenge brane-world dark matter models, suggesting a geometric unification of gravity and dark matter via Kaluza-Klein gauge bosons, with implications for cosmological observations.

Contribution

It demonstrates that quantum gravity constraints exclude branon dark matter in brane-world scenarios, proposing KK gauge bosons as dark matter candidates and linking gravity with dark matter geometrically.

Findings

Quantum gravity constraints rule out branon dark matter.

KK gauge bosons can serve as dark matter.

Potential observational signatures in CMB and gravitational waves.

Abstract

Based on the swampland program establishing the constraints that an effective field theory must satisfy in order to come from quantum gravity, we point to that if this program is true the brane-world scenario with the branon dark matter (DM) would be ruled out without needing the experimental observations. In other words, the constraints of quantum gravity imply that the branons must be absorbed by the Kaluza-Klein (KK) gauge bosons which are the off-diagonal components of the bulk metric to become their longitudinal modes. Interestingly, the KK gauge bosons behave as the DM and hence it leads to a geometric unification of gravity and the DM, as a natural feature of the brane-world scenario completed into quantum gravity in the ultraviolet. In addition, the KK gauge boson DM would open a particularly promising observation window to search for the DM coupling very weakly to the SM in the cosmic microwave background and the spectrum of the primordial gravitational waves.