Calculating Axion-Matter Couplings in String Theory
Abstract
In this work we calculate, for the first time, the dominant perturbative contributions to axion--matter couplings explicitly in string theory. Concretely, we compute these couplings in Calabi--Yau compactifications of heterotic string theory where the vector bundle is a sum of line bundles. They are expressed as overlap integrals requiring the Ricci-flat metric, the Hermitian Yang-Mills bundle metric, and the matter field harmonic forms. We compute these by solving the corresponding coupled differential equations with neural networks. Our results establish a characteristic hierarchy of four-dimensional couplings: axions couple to fermions as ℒ ⊃ cψ ∂μa/fa ψ† σ̅μψ with cψ an 𝒪(1) function of Kähler moduli for the model-dependent axions, while the corresponding coupling for the model-independent axion is suppressed by αYM at the ultraviolet matching scale. The model-dependent axions thus couple to fermions similarly as DFSZ-like four-dimensional axions, whereas the model-independent axion's couplings are loop-suppressed as in KSVZ-like constructions. The methods developed here apply directly to the large class of heterotic line bundle models with realistic spectra, and can be adapted to type II constructions.
Related
- Tachyon-massless couplings at order α' in bosonic string theory
- Tachyon-massless couplings at order α′ in bosonic string theory
- Circular Axion String Loop Simulations: Field Theory and Effective Description
- Majorana Neutrino Physics and Matter-Antimatter Asymmetry in Type IIA String Theory
- Axion couplings in orbifold GUTs
BibTeX
@misc{benabou2026calculating,
title = {{Calculating Axion-Matter Couplings in String Theory}},
author = {Joshua N. Benabou and Naomi Gendler and Thomas R. Harvey and Jakob Moritz},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.20911},
eprint = {2609.20911},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.20911},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Calculating Axion-Matter Couplings in String Theory
AU - Joshua N. Benabou
AU - Naomi Gendler
AU - Thomas R. Harvey
AU - Jakob Moritz
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2609.20911
UR - https://arxiv.org/abs/2609.20911
AB - In this work we calculate, for the first time, the dominant perturbative contributions to axion--matter couplings explicitly in string theory. Concretely, we compute these couplings in Calabi--Yau compactifications of heterotic string theory where the vector bundle is a sum of line bundles. They are expressed as overlap integrals requiring the Ricci-flat metric, the Hermitian Yang-Mills bundle metric, and the matter field harmonic forms. We compute these by solving the corresponding coupled differential equations with neural networks. Our results establish a characteristic hierarchy of four-dimensional couplings: axions couple to fermions as ℒ ⊃ c_ψ ∂_μa/f_a ψ^† σ̅^μψ with c_ψ an 𝒪(1) function of Kähler moduli for the model-dependent axions, while the corresponding coupling for the model-independent axion is suppressed by α_YM at the ultraviolet matching scale. The model-dependent axions thus couple to fermions similarly as DFSZ-like four-dimensional axions, whereas the model-independent axion's couplings are loop-suppressed as in KSVZ-like constructions. The methods developed here apply directly to the large class of heterotic line bundle models with realistic spectra, and can be adapted to type II constructions.
ER -