PreprintCC BY 4.0arXiv
Status of the strong CP problem
Abstract
The strong CP problem remains one of the major open questions in the Standard Model of particle physics. Its best-known solution is the Peccei--Quinn mechanism, which predicts a new pseudoscalar boson, the QCD axion. In recent years, alternative solutions and new perspectives on the foundations of the strong CP problem have also received renewed attention. In this review, we provide a pedagogical account of the underlying physics and summarise the current theoretical and phenomenological status of the problem.
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BibTeX
@misc{ai2026status,
title = {{Status of the strong $CP$ problem}},
author = {Wen-Yuan Ai},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.00620},
eprint = {2609.00620},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.00620},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Status of the strong CP problem
AU - Wen-Yuan Ai
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.00620
UR - https://arxiv.org/abs/2609.00620
AB - The strong CP problem remains one of the major open questions in the Standard Model of particle physics. Its best-known solution is the Peccei--Quinn mechanism, which predicts a new pseudoscalar boson, the QCD axion. In recent years, alternative solutions and new perspectives on the foundations of the strong CP problem have also received renewed attention. In this review, we provide a pedagogical account of the underlying physics and summarise the current theoretical and phenomenological status of the problem.
ER -