Axion Quality from Exact Proton Stability
Abstract
A discrete, anomaly-free ℤ9 gauge symmetry may persist to the deep infrared, exactly forbidding proton decay. This ℤ9 can emerge from Higgsing a lepton-flavour non-universal U(1)X that generates realistic neutrino masses and mixings through a high-scale seesaw and predicts an additional light Goldstone. Adding an anomaly-free chiral heavy-quark sector turns this mode into the QCD axion. The same selection rules that ban proton decay also forbid PQ-violating operators below a suitably high dimension, dPQ≳10, including operators involving the heavy quarks that radiatively match onto the scalar potential. We construct explicit models viable when PQ breaking occurs before or after inflation; in the latter case, avoiding stable heavy relics and eliminating the string-wall network tightly constrain the heavy-quark spectrum. We identify restricted regions of parameter space where thermal leptogenesis remains viable and, for dPQ≥13, can coexist with a high-quality axion constituting all of the dark matter.
Related
- Near-exact Upper Confidence Limits for Axion Haloscopes
- Stability Analysis of Axion Dark Energy Model
- Catastrophe Structure and Stability of Axion Stars
- Exact 1D Nonlinear Solutions for Proton-Driven Plasma Wakefields
- Stability Analysis of the Proton Hammerhead Distribution Observed by Parker Solar Probe: Linear Theory and Fully Kinetic Simulations under Idealised Conditions
BibTeX
@misc{davighi2026axion,
title = {{Axion Quality from Exact Proton Stability}},
author = {Joe Davighi and Admir Greljo and Xavier Ponce Díaz},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.01712},
eprint = {2609.01712},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.01712},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Axion Quality from Exact Proton Stability
AU - Joe Davighi
AU - Admir Greljo
AU - Xavier Ponce Díaz
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.01712
UR - https://arxiv.org/abs/2609.01712
AB - A discrete, anomaly-free ℤ_9 gauge symmetry may persist to the deep infrared, exactly forbidding proton decay. This ℤ_9 can emerge from Higgsing a lepton-flavour non-universal U(1)_X that generates realistic neutrino masses and mixings through a high-scale seesaw and predicts an additional light Goldstone. Adding an anomaly-free chiral heavy-quark sector turns this mode into the QCD axion. The same selection rules that ban proton decay also forbid PQ-violating operators below a suitably high dimension, d_PQ≳10, including operators involving the heavy quarks that radiatively match onto the scalar potential. We construct explicit models viable when PQ breaking occurs before or after inflation; in the latter case, avoiding stable heavy relics and eliminating the string-wall network tightly constrain the heavy-quark spectrum. We identify restricted regions of parameter space where thermal leptogenesis remains viable and, for d_PQ≥13, can coexist with a high-quality axion constituting all of the dark matter.
ER -