- Physical Review Journals
All JournalsPhysics Magazine

Physical Review D

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

Astrophysical consequences of an electroweak ηw pseudoscalar

Hooman Davoudiasl*

  • *Contact author: hooman@bnl.gov
PDF

Phys. Rev. D 113, 023039 – Published 21 January, 2026

DOI: https://doi.org/10.1103/qm4d-1n3d

Abstract

Recently, it has been suggested that the spectrum of physical states in the Standard Model may include an ultralight pseudoscalar, denoted by ηw, in analogy with the η′ state arising from the strong interactions. We find that typical expectations for the properties of ηw get challenged by astrophysical constraints on the couplings of ultralight bosons. Our strongest limit sets a lower bound of O(100  TeV) on the decay constant of the hypothesized pseudoscalar. We also briefly discuss whether ηw could be a dark matter candidate, or the origin of dark energy, but conclude that those identifications appear unlikely. Given the important implications of a potentially overlooked ηw state for a more complete understanding of the electroweak interactions and a fundamental description of nature, further theoretical and phenomenological investigations of this possibility and its associated physics are warranted.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (25)

  1. G. Dvali, A. Kobakhidze, and O. Sakhelashvili, Electroweak ηw meson, Phys. Rev. D 111, 113002 (2025).
  2. G. Dvali, A. Kobakhidze, and O. Sakhelashvili, ηw-meson from topological properties of the electroweak vacuum, Phys. Rev. D 112, 093006 (2025).
  3. A. A. Anselm and A. A. Johansen, Baryon nonconservation in standard model and Yukawa interaction, Nucl. Phys. B407, 313 (1993).
  4. A. A. Anselm and A. A. Johansen, Can electroweak theta term be observable?, Nucl. Phys. B412, 553 (1994).
  5. P. Fileviez Perez and H. H. Patel, The electroweak vacuum angle, Phys. Lett. B 732, 241 (2014).
  6. E. Witten, Current algebra theorems for the U(1) goldstone boson, Nucl. Phys. B156, 269 (1979).
  7. G. Cacciapaglia, F. Sannino, and J. Turner, Hiding in plain sight, the electroweak ηW, arXiv:2509.15912.
  8. L. McLerran, R. Pisarski, and V. Skokov, Electroweak instantons, axions, and the cosmological constant, Phys. Lett. B 713, 301 (2012).
  9. M. Bauer, M. Neubert, and A. Thamm, Collider probes of axion-like particles, J. High Energy Phys. 12 2017 044.
  10. N. Craig, A. Hook, and S. Kasko, The photophobic ALP, J. High Energy Phys. 09 (2018) 028.
  11. J. Heeck and H. H. Patel, Majoron at two loops, Phys. Rev. D 100, 095015 (2019).
  12. D. J. E. Marsh, Axion cosmology, Phys. Rep. 643, 1 (2016).
  13. G. Raffelt and A. Weiss, Red giant bound on the axion—electron coupling revisited, Phys. Rev. D 51, 1495 (1995).
  14. G. G. Raffelt, Astrophysical axion bounds, Lect. Notes Phys. 741, 51 (2008).
  15. A. Caputo and G. Raffelt, Astrophysical axion bounds: The 2024 edition, Proc. Sci. COSMICWISPers (2024) 041 [arXiv:2401.13728].
  16. G. Cacciapaglia, F. Sannino, and J. Turner, The good qualities of the weak axion, arXiv:2510.14104.
  17. R. Bollig, W. DeRocco, P. W. Graham, and H.-T. Janka, Muons in supernovae: Implications for the axion-muon coupling, Phys. Rev. Lett. 125, 051104 (2020); 126, 189901(E) (2021).
  18. D. Croon, G. Elor, R. K. Leane, and S. D. McDermott, Supernova muons: New constraints on Z’ bosons, axions and ALPs, J. High Energy Phys. 01 (2021) 107.
  19. S. Navas et al. (Particle Data Group), Review of particle physics, Phys. Rev. D 110, 030001 (2024).
  20. R. L. Jaffe, Perhaps a stable dihyperon, Phys. Rev. Lett. 38, 195 (1977); 38, 617(E) (1977).
  21. G. R. Farrar and G. Zaharijas, Nuclear and nucleon transitions of the H dibaryon, Phys. Rev. D 70, 014008 (2004).
  22. G. R. Farrar, 6-quark dark matter, Proc. Sci. ICRC2017 (2018) 929 [arXiv:1711.10971].
  23. E. W. Kolb and M. S. Turner, Dibaryons cannot be the dark matter, Phys. Rev. D 99, 063519 (2019).
  24. S. D. McDermott, S. Reddy, and S. Sen, Deeply bound dibaryon is incompatible with neutron stars and supernovae, Phys. Rev. D 99, 035013 (2019).
  25. G. Choi, W. Lin, L. Visinelli, and T. T. Yanagida, Cosmic birefringence and electroweak axion dark energy, Phys. Rev. D 104, L101302 (2021).

Outline

Information

Phys. Rev. D 113, 023039– Published 21 January, 2026
  • Received 17 October 2025
  • Accepted 8 January 2026
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation