- 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

CMB constraints on loop-induced decays of leptophilic dark matter

Gabriele Montefalcone1,*, Gilly Elor1, Kimberly K. Boddy1, and Nicola Bellomo1,2,3,4

  • *Contact author: montefalcone@utexas.edu
PDF

Phys. Rev. D 112, 023506 – Published 7 July, 2025

DOI: https://doi.org/10.1103/hxmm-vcjz

Abstract

Leptophilic sub-MeV spin-zero dark matter (DM) decays into photons via one-loop processes, a scenario that has been in part overlooked in current literature. In this work, we provide updated and comprehensive upper limits on scalar, pseudoscalar, and axionlike DM-electron couplings based on the latest NPIPE cosmic microwave background data from Planck. Our bounds on the couplings are not only competitive with astrophysical and terrestrial experiments, but outperform them in certain regions of parameter space. Notably, we present the most stringent limits to date on scalar DM with masses around a few keV and pseudoscalar DM with masses between 100 eV and a few keV. Additionally, we explore, for the first time, the impact of implementing a cosmology-consistent treatment of energy deposition into the cosmic medium.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (86)

  1. S. Weinberg, A new light boson?, Phys. Rev. Lett. 40, 223 (1978).
  2. C. B. Adams et al., Axion dark matter, in Snowmass 2021 (2022), arXiv:2203.14923.
  3. K. Choi, S. H. Im, and C. Sub Shin, Recent progress in the physics of axions and axion-like particles, Annu. Rev. Nucl. Part. Sci. 71, 225 (2021).
  4. G. G. Raffelt, Axions: Motivation, limits and searches, J. Phys. A 40, 6607 (2007).
  5. B. Batell, A. Ghalsasi, and M. Rai, Dynamics of dark matter misalignment through the Higgs portal, J. High Energy Phys. 01 (2024) 038.
  6. J. Preskill, M. B. Wise, and F. Wilczek, Cosmology of the invisible axion, Phys. Lett. 120B, 127 (1983).
  7. M. Dine and W. Fischler, The not-so-harmless axion, Phys. Lett. 120B, 137 (1983).
  8. R. Davis, Cosmic axions from cosmic strings, Phys. Lett. B 180, 225 (1986).
  9. M. Gorghetto, E. Hardy, and G. Villadoro, Axions from strings: The attractive solution, J. High Energy Phys. 07 (2018) 151.
  10. M. Gorghetto, E. Hardy, and G. Villadoro, More axions from strings, SciPost Phys. 10, 050 (2021).
  11. D. H. Lyth, Axions and inflation: Sitting in the vacuum, Phys. Rev. D 45, 3394 (1992).
  12. R. T. Co, L. J. Hall, and K. Harigaya, Axion kinetic misalignment mechanism, Phys. Rev. Lett. 124, 251802 (2020).
  13. R. T. Co, E. Gonzalez, and K. Harigaya, Axion misalignment driven to the Hilltop, J. High Energy Phys. 05 (2019) 163.
  14. R. T. Co, L. J. Hall, K. Harigaya, K. A. Olive, and S. Verner, Axion kinetic misalignment and parametric resonance from inflation, J. Cosmol. Astropart. Phys. 08 (2020) 036.
  15. J. A. R. Cembranos, L. J. Garay, and J. M. Sánchez Velázquez, Gravitational production of scalar dark matter, J. High Energy Phys. 06 (2020) 084.
  16. C. Boehm, T. A. Ensslin, and J. Silk, Can annihilating dark matter be lighter than a few GeVs?, J. Phys. G 30, 279 (2004).
  17. P. D. Serpico and G. G. Raffelt, MeV-mass dark matter and primordial nucleosynthesis, Phys. Rev. D 70, 043526 (2004).
  18. K. M. Nollett and G. Steigman, BBN and the CMB constrain light, electromagnetically coupled WIMPs, Phys. Rev. D 89, 083508 (2014).
  19. G. Steigman and K. M. Nollett, Light WIMPs, equivalent neutrinos, BBN, and the CMB, Mem. Soc. Astron. Ital. 85, 175 (2014).
  20. K. M. Nollett and G. Steigman, BBN and the CMB constrain neutrino coupled light WIMPs, Phys. Rev. D 91, 083505 (2015).
  21. M. Escudero, Neutrino decoupling beyond the standard model: CMB constraints on the dark matter mass with a fast and precise Neff evaluation, J. Cosmol. Astropart. Phys. 02 (2019) 007.
  22. N. Sabti, J. Alvey, M. Escudero, M. Fairbairn, and D. Blas, Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB, J. Cosmol. Astropart. Phys. 01 (2020) 004.
  23. C. Giovanetti, M. Lisanti, H. Liu, and J. T. Ruderman, Joint cosmic microwave background and big bang nucleosynthesis constraints on light dark sectors with dark radiation, Phys. Rev. Lett. 129, 021302 (2022).
  24. R. An, V. Gluscevic, E. Calabrese, and J. C. Hill, What does cosmology tell us about the mass of thermal-relic dark matter?, J. Cosmol. Astropart. Phys. 07 (2022) 002.
  25. R. An, K. K. Boddy, and V. Gluscevic, Interacting light thermal-relic dark matter: Self-consistent cosmological bounds, Phys. Rev. D 109, 123522 (2024).
  26. A. Mitridate, T. Trickle, Z. Zhang, and K. M. Zurek, Dark matter absorption via electronic excitations, J. High Energy Phys. 09 (2021) 123.
  27. S. Knapen, T. Lin, and K. M. Zurek, Light dark matter: Models and constraints, Phys. Rev. D 96, 115021 (2017).
  28. R. Essig, E. Kuflik, S. D. McDermott, T. Volansky, and K. M. Zurek, Constraining light dark matter with diffuse x-ray and gamma-ray observations, J. High Energy Phys. 11 (2013) 193.
  29. J. A. Adams, S. Sarkar, and D. W. Sciama, CMB anisotropy in the decaying neutrino cosmology, Mon. Not. R. Astron. Soc. 301, 210 (1998).
  30. X.-L. Chen and M. Kamionkowski, Particle decays during the cosmic dark ages, Phys. Rev. D 70, 043502 (2004).
  31. D. P. Finkbeiner, S. Galli, T. Lin, and T. R. Slatyer, Searching for dark matter in the CMB: A compact parametrization of energy injection from new physics, Phys. Rev. D 85, 043522 (2012).
  32. T. R. Slatyer, Energy injection and absorption in the cosmic dark ages, Phys. Rev. D 87, 123513 (2013).
  33. V. Poulin, P. D. Serpico, and J. Lesgourgues, A fresh look at linear cosmological constraints on a decaying dark matter component, J. Cosmol. Astropart. Phys. 08 (2016) 036.
  34. T. R. Slatyer and C.-L. Wu, General constraints on dark matter decay from the cosmic microwave background, Phys. Rev. D 95, 023010 (2017).
  35. H. Liu, T. R. Slatyer, and J. Zavala, Contributions to cosmic reionization from dark matter annihilation and decay, Phys. Rev. D 94, 063507 (2016).
  36. V. Poulin, J. Lesgourgues, and P. D. Serpico, Cosmological constraints on exotic injection of electromagnetic energy, J. Cosmol. Astropart. Phys. 03 (2017) 043.
  37. J. Cang, Y. Gao, and Y.-Z. Ma, Probing dark matter with future CMB measurements, Phys. Rev. D 102, 103005 (2020).
  38. H. Liu, W. Qin, G. W. Ridgway, and T. R. Slatyer, Exotic energy injection in the early Universe. II. CMB spectral distortions and constraints on light dark matter, Phys. Rev. D 108, 043531 (2023).
  39. F. Capozzi, R. Z. Ferreira, L. Lopez-Honorez, and O. Mena, CMB and Lyman-α constraints on dark matter decays to photons, J. Cosmol. Astropart. Phys. 06 (2023) 060.
  40. C. Xu, W. Qin, and T. R. Slatyer, CMB limits on decaying dark matter beyond the ionization threshold, Phys. Rev. D 110, 123529.
  41. H. Liu, G. W. Ridgway, and T. R. Slatyer, Code package for calculating modified cosmic ionization and thermal histories with dark matter and other exotic energy injections, Phys. Rev. D 101, 023530 (2020).
  42. H. Liu, W. Qin, G. W. Ridgway, and T. R. Slatyer, Exotic energy injection in the early Universe. I. A novel treatment for low-energy electrons and photons, Phys. Rev. D 108, 043530 (2023).
  43. P. Stöcker, M. Krämer, J. Lesgourgues, and V. Poulin, Exotic energy injection with exoclass: Application to the Higgs portal model and evaporating black holes, J. Cosmol. Astropart. Phys. 03 (2018) 018.
  44. D. Blas, J. Lesgourgues, and T. Tram, The Cosmic Linear Anisotropy Solving System (class) II: Approximation schemes, J. Cosmol. Astropart. Phys. 07 (2011) 034.
  45. Y. Akrami et al. (Planck Collaboration), Planck intermediate results. LVII. Joint Planck LFI and HFI data processing, Astron. Astrophys. 643, A42 (2020).
  46. J. Quevillon and C. Smith, Axions are blind to anomalies, Eur. Phys. J. C 79, 822 (2019).
  47. R. Z. Ferreira, M. C. D. Marsh, and E. Müller, Strong supernovae bounds on ALPs from quantum loops, J. Cosmol. Astropart. Phys. 11 (2022) 057.
  48. D. Green, Y. Guo, and B. Wallisch, Cosmological implications of axion-matter couplings, J. Cosmol. Astropart. Phys. 02 (2022) 019.
  49. M. Tristram et al., Cosmological parameters derived from the final Planck data release (PR4), Astron. Astrophys. 682, A37 (2024).
  50. N. Aghanim et al. (Planck Collaboration). Planck 2018 results. V. CMB power spectra and likelihoods, Astron. Astrophys. 641, A5 (2020).
  51. J. Carron, M. Mirmelstein, and A. Lewis, CMB lensing from Planck PR4 maps, J. Cosmol. Astropart. Phys. 09 (2022) 039.
  52. Z. Li, V. Gluscevic, K. K. Boddy, and M. S. Madhavacheril, Disentangling dark physics with cosmic microwave background experiments, Phys. Rev. D 98, 123524 (2018).
  53. B. Audren, J. Lesgourgues, K. Benabed, and S. Prunet, Conservative constraints on early cosmology: An illustration of the montepython cosmological parameter inference code, J. Cosmol. Astropart. Phys. 02 (2013) 001.
  54. T. Brinckmann and J. Lesgourgues, montepython 3: Boosted MCMC sampler and other features, Phys. Dark Universe 24, 100260 (2019).
  55. A. Gelman and D. Rubin, Inference from iterative simulation using multiple sequences, Stat. Sci. 7, 457 (1992).
  56. A. Lewis, getdist: A python package for analysing Monte Carlo samples, arXiv:1910.13970.
  57. R. Ziegler, Flavored axions, Proc. Sci. CORFU2018 (2019) 035 [arXiv:1905.01084].
  58. P. Panci, D. Redigolo, T. Schwetz, R. Ziegler, Axion dark matter from lepton flavor-violating decays, Phys. Lett. B 841, 137919 (2023).
  59. R. Ziegler, Flavor probes of axion dark matter, Proc. Sci. DISCRETE2022 (2024) 086 [arXiv:2303.13353].
  60. M. Bauer, M. Neubert, S. Renner, M. Schnubel, and A. Thamm, Flavor probes of axion-like particles, J. High Energy Phys. 09 (2022) 056.
  61. H. Li, Z. Liu, and N. Song, Probing axion and muon-philic new physics with muon beam dump, arXiv:2501.06294.
  62. 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).
  63. 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.
  64. A. Caputo, G. Raffelt, and E. Vitagliano, Muonic boson limits: Supernova redux, Phys. Rev. D 105, 035022 (2022).
  65. E. Hardy and R. Lasenby, Stellar cooling bounds on new light particles: Plasma mixing effects, J. High Energy Phys. 02 (2017) 033.
  66. K. C. Y. Ng, B. M. Roach, K. Perez, J. F. Beacom, S. Horiuchi, R. Krivonos, and D. R. Wik, New constraints on sterile neutrino dark matter from NuSTAR M31 observations, Phys. Rev. D 99, 083005 (2019).
  67. R. Laha, J. B. Muñoz, and T. R. Slatyer, INTEGRAL constraints on primordial black holes and particle dark matter, Phys. Rev. D 101, 123514 (2020).
  68. J. W. Foster, M. Kongsore, C. Dessert, Y. Park, N. L. Rodd, K. Cranmer, and B. R. Safdi, Deep search for decaying dark matter with XMM-Newton Blank-sky observations, Phys. Rev. Lett. 127, 051101 (2021).
  69. R. Z. Ferreira, M. C. D. Marsh, and E. Müller, Do direct detection experiments constrain axionlike particles coupled to electrons?, Phys. Rev. Lett. 128, 221302 (2022).
  70. 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).
  71. P. Agnes et al. (DarkSide Collaboration), Search for dark matter particle interactions with electron final states with DarkSide-50, Phys. Rev. Lett. 130, 101002 (2023).
  72. X. Zeng et al. (PandaX Collaboration), Exploring new physics with PandaX-4T low energy electronic recoil data, Phys. Rev. Lett. 134, 041001 (2025).
  73. T. Li et al. (PandaX Collaboration), Searching for MeV-scale axion-like particles and dark photons with PandaX-4T, Phys. Rev. Lett. 134, 071004 (2025).
  74. E. Aprile et al. (XENON Collaboration), Light dark matter search with ionization signals in XENON1T, Phys. Rev. Lett. 123, 251801 (2019).
  75. E. Aprile et al. (XENON Collaboration), Excess electronic recoil events in XENON1T, Phys. Rev. D 102, 072004 (2020).
  76. E. Aprile et al. (XENON Collaboration), Emission of single and few electrons in XENON1T and limits on light dark matter, Phys. Rev. D 106, 022001 (2022).
  77. E. Aprile et al. (XENON Collaboration), Search for new physics in electronic recoil data from XENONnT, Phys. Rev. Lett. 129, 161805 (2022).
  78. T. Aralis et al. (SuperCDMS Collaboration), Constraints on dark photons and axionlike particles from the SuperCDMS Soudan experiment, Phys. Rev. D 101, 052008 (2020); 103, 039901(E) (2021).
  79. E. Armengaud et al. (EDELWEISS Collaboration), Searches for electron interactions induced by new physics in the EDELWEISS-III germanium bolometers, Phys. Rev. D 98, 082004 (2018).
  80. M. Agostini et al. (GERDA Collaboration), First search for bosonic superweakly interacting massive particles with masses up to 1  MeV/c2 with GERDA, Phys. Rev. Lett. 125, 011801 (2020); 129, 089901(E) (2022).
  81. S. Bottaro, A. Caputo, G. Raffelt, and E. Vitagliano, Stellar limits on scalars from electron-nucleus bremsstrahlung, J. Cosmol. Astropart. Phys. 07 (2023) 071.
  82. F. Pérez and B. Granger, ipython: A system for interactive scientific computing, Comput. Sci. Eng. 9, 21 (2007).
  83. J. Hunter, matplotlib: A 2D graphics environment, Comput. Sci. Eng. 9, 90 (2007).
  84. C. Harris et al., Array programming with numpy, Nature (London) 585, 357 (2020).
  85. P. Virtanen et al., scipy 1.0—Fundamental algorithms for scientific computing in python, Nat. Methods 17, 261 (2020).
  86. C. O’Hare, cajohare/axionlimits: Axionlimits, https://cajohare.github.io/AxionLimits/ (2020).

Outline

Information

Phys. Rev. D 112, 023506– Published 7 July, 2025
  • Received 26 March 2025
  • Accepted 25 June 2025
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