cff-version: 1.2.0
message: If you use results from this problem page, please cite it as below.
title: "Cairn Commons — The strong CP problem"
type: dataset
license: CC-BY-4.0
url: "https://cairn-commons.com/problems/strong-cp-problem"
date-released: 2026-09-28
authors:
  - name: Cairn Commons contributors
keywords:
  - "physics_theory"
  - "qcd"
  - "cp-violation"
  - "axions"
  - "neutron-edm"
  - "beyond-standard-model"