Fine-tuning problems in type IIA string theory
Abstract
We demonstrate a unified resolution to the strong CP, hierarchy, and cosmological constant problems in type IIA flux compactifications, via 4-form fluxes and KL stabilization. We show that the strong CP problem can be effectively "solved" in type IIA orientifold constructions, particularly in the type IIA model. Building on this, we explore whether the remaining two fine-tuning problems can also be resolved within the same setup. To obtain a small cosmological constant, we adopt the KL scenario and find that, in order to avoid conflicts with the swampland distance conjecture and to eliminate the need for fine-tuning, the perturbative superpotential must take the form . Additionally, we compute the gravitino mass. This allows for a resolution of the hierarchy problem without introducing fine-tuning if gravitino mass lies below 100 TeV. Taken together, these results suggest that the type IIA orientifold model provides a promising framework in which all three fine-tuning problems may be addressed simultaneously.
Cite
@article{arxiv.2506.12993,
title = {Fine-tuning problems in type IIA string theory},
author = {Yang Liu},
journal= {arXiv preprint arXiv:2506.12993},
year = {2025}
}