Universality in the Axiverse

Abstract: Studies of axion effective theories in the type IIB Calabi-Yau landscape have revealed that hierarchies in cycle volumes drive correlations between axion physics and the number of axions in a given model. We analyze distributions of divisor volumes in toric hypersurface Calabi-Yau threefolds, and provide evidence that aspects of these distributions are universal across this landscape. Furthermore, we show that axion observables in this landscape can be approximated efficiently in terms of only divisor volumes. Finally, we propose a simple model for the spectrum of divisor volumes and use this model to reproduce results on axion masses and decay constants across the Kreuzer-Skarke axiverse.