English

Fine-tuning problems in type IIA string theory

High Energy Physics - Theory 2025-06-17 v1

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 T6/(Z2×Z2)T^6/(\mathbb{Z}_2 \times \mathbb{Z}_2) 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 ΔW\Delta W must take the form f0U3f_0 U^3. 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 T6/(Z2×Z2)T^6/(\mathbb{Z}_2 \times \mathbb{Z}_2) orientifold model provides a promising framework in which all three fine-tuning problems may be addressed simultaneously.

Keywords

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}
}
R2 v1 2026-07-01T03:18:43.909Z