Axionic Quintessence in Heterotic String Theory

@misc{andriot2026axionic,
  title = {{Axionic Quintessence in Heterotic String Theory}},
  author = {David Andriot and Margherita Putti and Leo Veissiere},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.36064},
  eprint = {2610.36064},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.36064},
}

TY  - UNPB
TI  - Axionic Quintessence in Heterotic String Theory
AU  - David Andriot
AU  - Margherita Putti
AU  - Leo Veissiere
PY  - 2026
DA  - 2026/10/26
PB  - arXiv
DO  - 10.48550/arxiv.2610.36064
UR  - https://arxiv.org/abs/2610.36064
AB  - We investigate axionic quintessence in heterotic string compactifications. Starting from the ten-dimensional theory, we derive the four-dimensional axion effective action, including gauge couplings and non-perturbative potentials, and identify the curvature terms that can correct it. We examine the geometric requirements for ultralight axions generated by exponentially suppressed worldsheet instantons, finding significant restrictions through an exploratory scan of toric Calabi-Yau hypersurfaces. In an illustrative K3-fibred setup, the minimal benchmark also encounters a tension with the positivity of the one-loop corrected gauge kinetic functions. Aligned worldsheet-instanton contributions provide a way to alleviate this tension and yield an ultralight axion with a phenomenologically relevant decay constant. Our analysis also identifies lower-action instantons whose contributions must be controlled to preserve the ultralight axion. We then study the resulting class of quintessence potentials and qualitatively compare their late-time cosmological solutions with observationally preferred ranges.
ER  -