Probing the Dark Dimension with Auger data

Understand

[Abridged] By combining swampland conjectures with observational data, it was recently noted that our universe could stretch off in an asymptotic region of the string landscape of vacua.

• In this framework, the cosmological hierarchy problem can be resolved by the addition of one mesoscopic (dark) dimension of size $\sim \lambda \, \Lambda^{-1/4} \sim 1~\mu{\rm m}$.
• The Planck scale of the higher dimensional theory, $M_{\rm UV} \sim \lambda^{-1/3} \Lambda^{1/12} M_{\rm Pl}^{2/3} \sim 10^{10}~{\rm GeV}$, is tantalizingly close to the energy above which the TA and Auger collaborations found conclusive evidence for a sharp cutoff of the flux of UHECRs.
• It was recently suggested that since physics becomes strongly coupled to gravity beyond $M_{\rm UV}$, universal features deep-rooted in the dark dimension could control the energy cutoff of the source spectra.