Randall-Sundrum and Flipped SU(5)
  In this letter, we construct a model based on a flipped SU(5) partial grand unified theory, within the framework of the Randall-Sundrum (RS1) proposal. Breaking of $\widetilde{SU}(5)$ is achieved using a bulk scalar field in the \textbf{10} of SU(5), $\Phi$, which gains a vacuum expectation value $\left< \Phi\right> \sim 3 \times 10^{15}$ GeV. We are able to retain the successes of the flipped SU(5) phenomenology, namely the elimination of the doublet-triplet splitting problem and the confinement of all fields to the smallest (\textbf{1}, $\mathbf{\bar{5}}$, and \textbf{10}) representations of SU(5). We derive the beta functions, and point out some constraints on bulk matter content implied by the runnings (and positivity) of the five dimensional coupling. Finally, we comment on baryon decay and show the fine-tuning problem required to prevent an exponentially short proton lifetime. 
Ben Dundee and Gerald B. Cleaver