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  • Featured in Physics
  • Open Access

Possible Solution to the Gallium Anomaly Moving beyond the Leptonic Wave-Function Factorization

M. Cadeddu1,*, N. Cargioli1,†, F. Dordei1,‡, L. Ferro2,1,§, C. Giunti3,∥, and M. Pitzalis2,1,¶

  • *Contact author: matteo.cadeddu@ca.infn.it
  • †Contact author: nicola.cargioli@ca.infn.it
  • ‡Contact author: francesca.dordei@cern.ch
  • §Contact author: luca.ferro@ca.infn.it
  • ∥Contact author: carlo.giunti@to.infn.it
  • Contact author: matilde.pitzalis@ca.infn.it
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Phys. Rev. Lett. 137, 131805 – Published 24 September, 2026

DOI: https://doi.org/10.1103/5pvf-mcr1

This article was published on 24 September, 2026. Please update your links.

Abstract

For over 30 years, a ∼20% deficit, now exceeding 5σ, has persisted between measured and predicted neutrino capture rates on Ga71, as observed in radioactive source experiments (namely GALLEX, SAGE, and more recently BEST) using Cr51 and Ar37. This long-standing discrepancy, referred to as the gallium anomaly, has posed a significant challenge to our understanding of both experimental methods and theoretical predictions. In this Letter, we revisit the theoretical calculation of the neutrino capture cross section by moving beyond the standard treatment of the leptonic wave functions, revealing limitations in the commonly used factorization approach based on the detailed balance principle. Incorporating phenomenologically constrained Gamow-Teller transition densities, able to correctly reproduce the precisely measured half-life of Ge71, we find that the revised cross section can be significantly reduced, potentially resolving the gallium anomaly without invoking new physics.

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synopsis

Gallium Anomaly May Finally Be Explained

Published 24 September, 2026

A decades-old neutrino mystery might be solved not by undiscovered physics but by improved calculations.

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References (81)

  1. S. R. Elliott, V. Gavrin, and W. Haxton, Prog. Part. Nucl. Phys. 134, 104082 (2024).
  2. C. Giunti and M. Laveder, Phys. Rev. C 83, 065504 (2011).
  3. P. Anselmann et al., Phys. Lett. B 285, 376 (1992).
  4. W. Hampel et al., Phys. Lett. B 447, 127 (1999).
  5. F. Kaether, W. Hampel, G. Heusser, J. Kiko, and T. Kirsten, Phys. Lett. B 685, 47 (2010).
  6. M. Altmann et al. (GNO Collaboration), Phys. Lett. B 616, 174 (2005).
  7. J. N. Abdurashitov et al. (SAGE Collaboration), Phys. Rev. C 80, 015807 (2009).
  8. V. N. Gavrin, The history, present and future of SAGE (Soviet-American Gallium Experiment), in Solar Neutrinos, edited by M. Meyer and K. Zuber (World Scientific Publishing Co. Pte. Ltd., Singapore, 2019), pp. 29–46, 10.1142/9789811204296_0002.
  9. V. V. Barinov et al., Phys. Rev. Lett. 128, 232501 (2022).
  10. V. V. Barinov et al., Phys. Rev. C 105, 065502 (2022).
  11. M. Cadeddu, N. Cargioli, G. Carotenuto, F. Dordei, L. Ferro, and C. Giunti, Phys. Rev. D 113, 033006 (2026).
  12. G. Mention, M. Fechner, T. Lasserre, T. A. Mueller, D. Lhuillier, M. Cribier, and A. Letourneau, Phys. Rev. D 83, 073006 (2011).
  13. P. Abratenko et al. (MicroBooNE Collaboration), Phys. Rev. Lett. 130, 011801 (2023).
  14. C. Giunti, Y. F. Li, C. A. Ternes, O. Tyagi, and Z. Xin, J. High Energy Phys. 10 (2022) 164.
  15. J. M. Berryman and P. Huber, Phys. Rev. D 101, 015008 (2020).
  16. C. Giunti and M. Laveder, Mod. Phys. Lett. A 22, 2499 (2007).
  17. C. Giunti and T. Lasserre, Annu. Rev. Nucl. Part. Sci. 69, 163 (2019).
  18. S. Gariazzo, C. Giunti, M. Laveder, Y. F. Li, and E. M. Zavanin, J. Phys. G 43, 033001 (2016).
  19. M. C. Gonzalez-Garcia, M. Maltoni, and T. Schwetz, Nucl. Phys. B908, 199 (2016).
  20. A. Diaz, C. A. Argüelles, G. H. Collin, J. M. Conrad, and M. H. Shaevitz, Phys. Rep. 884, 1 (2020).
  21. S. Böser, C. Buck, C. Giunti, J. Lesgourgues, L. Ludhova, S. Mertens, A. Schukraft, and M. Wurm, Prog. Part. Nucl. Phys. 111, 103736 (2020).
  22. B. Dasgupta and J. Kopp, Phys. Rep. 928, 1 (2021).
  23. C. Giunti and C. A. Ternes, Phys. Lett. B 849, 138436 (2024).
  24. K. N. Abazajian et al., arXiv:1204.5379.
  25. M. A. Acero et al., J. Phys. G 51, 120501 (2024).
  26. Y. Farzan and T. Schwetz, SciPost Phys. 15, 172 (2023).
  27. C. Giunti, Y. F. Li, C. A. Ternes, and Z. Xin, Phys. Lett. B 829, 137054 (2022).
  28. H. Almazán et al. (STEREO Collaboration), Nature (London) 613, 257 (2023).
  29. I. Machikhiliyan (DANSS Collaboration), Phys. Part. Nucl. 53, 546 (2022).
  30. M. Andriamirado et al. (PROSPECT Collaboration), Phys. Rev. Lett. 134, 151802 (2025).
  31. K. Goldhagen, M. Maltoni, S. E. Reichard, and T. Schwetz, Eur. Phys. J. C 82, 116 (2022).
  32. M. C. Gonzalez-Garcia, M. Maltoni, and J. P. Pinheiro, Phys. Lett. B 862, 139297 (2025).
  33. P. Abratenko et al. (MicroBooNE Collaboration), Nature (London) 648, 64 (2025).
  34. H. Acharya et al. (KATRIN Collaboration), Nature (London) 648, 70 (2025).
  35. P. Huber, Nature (London) 648, 40 (2025).
  36. J. N. Bahcall, Phys. Rev. C 56, 3391 (1997).
  37. S. R. Elliott, V. N. Gavrin, W. C. Haxton, T. V. Ibragimova, and E. J. Rule, Phys. Rev. C 108, 035502 (2023).
  38. W. C. Haxton and E. Rule, Phys. Lett. B 861, 139259 (2025).
  39. J. Kostensalo, J. Suhonen, C. Giunti, and P. C. Srivastava, Phys. Lett. B 795, 542 (2019); 846, 138190(E) (2023).
  40. V. Brdar, J. Gehrlein, and J. Kopp, J. High Energy Phys. 05 (2023) 143.
  41. C. Giunti, Y. F. Li, C. A. Ternes, and Z. Xin, Phys. Lett. B 842, 137983 (2023).
  42. P. Huber, Phys. Rev. D 107, 096011 (2023).
  43. W. S. C. Williams, An Introduction to Elementary Particles (Academic Press, New York, 1971).
  44. J. M. Blatt and V. F. Weisskopf, Theoretical Nuclear Physics (Springer, New York, 1952).
  45. L. W. Alvarez, A Proposed Experimental Test of the Neutrino Theory (Lawrence Berkeley National Laboratory, 1949), 10.2172/929771.
  46. J. N. Bahcall, Neutrino Astrophysics (Cambridge University Press, New York, 1989).
  47. J. N. Bahcall, Rev. Mod. Phys. 50, 881 (1978).
  48. J. N. Bahcall, Phys. Rev. 135, B137 (1964).
  49. S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024).
  50. B. Märkisch, H. Mest, H. Saul, X. Wang, H. Abele, D. Dubbers, M. Klopf, A. Petoukhov, C. Roick, T. Soldner, and D. Werder, Phys. Rev. Lett. 122, 242501 (2019).
  51. W. Hampel and L. P. Remsberg, Phys. Rev. C 31, 666 (1985).
  52. J. I. Collar and S. G. Yoon, Phys. Rev. C 108, L021602 (2023).
  53. E. B. Norman, A. Drobizhev, N. Gharibyan, K. E. Gregorich, Y. G. Kolomensky, B. N. Sammis, N. D. Scielzo, J. A. Shusterman, and K. J. Thomas, Phys. Rev. C 109, 055501 (2024).
  54. A. Derbin, I. Drachnev, D. Ivanov, V. Muratova, M. Trushin, E. Unzhakov, and A. Vorobyev, Phys. At. Nucl. 88, 52 (2025).
  55. E. Fermi, Ric. Sci. 4, 491 (1933).
  56. F. Salvat and J. M. Fernández-Varea, Comput. Phys. Commun. 240, 165 (2019).
  57. C. Froese Fischer, G. Gaigalas, P. Jönsson, and J. Bieroń, Comput. Phys. Commun. 237, 184 (2019).
  58. S. Wang et al., Phys. Lett. B 856, 138867 (2024).
  59. W. Bambynek, H. Behrens, M. H. Chen, B. Crasemann, M. L. Fitzpatrick, K. W. D. Ledingham, H. Genz, M. Mutterer, and R. L. Intemann, Rev. Mod. Phys. 49, 77 (1977).
  60. B. Singh and J. Chen, Nucl. Data Sheets 188, 1 (2023).
  61. D. Krofcheck, E. Sugarbaker, J. Rapaport, D. Wang, J. N. Bahcall, R. C. Byrd, C. C. Foster, C. D. Goodman, I. J. Van Heerden, C. Gaarde, J. S. Larsen, D. J. Horen, and T. N. Taddeucci, Phys. Rev. Lett. 55, 1051 (1985).
  62. D. Frekers et al., Phys. Lett. B 706, 134 (2011).
  63. E. Konopinski, The Theory of Beta Radioactivity, International Series of Monographs on Physics (Clarendon P., Oxford, 1966).
  64. K. Koshigiri, M. Nishimura, H. Ohtsubo, and M. Morita, Nucl. Phys. A319, 301 (1979).
  65. S. Raman, C. A. Houser, T. A. Walkiewicz, and I. S. Towner, At. Data Nucl. Data Tables 21, 567 (1978); 22, 369(E) (1978).
  66. W. Horiuchi, T. Sato, Y. Uesaka, and K. Yoshida, Prog. Theor. Exp. Phys. 2021, 103D03 (2021).
  67. G. B. King, L. Andreoli, S. Pastore, and M. Piarulli, Front. Phys. 8, 363 (2020).
  68. H. Behrens and J. Jänecke, Numerical Tables for Beta-Decay and Electron Capture, edited by H. Schopper, Landolt-Boernstein—Group I Elementary Particles, Nuclei and Atoms (Springer-Verlag, Berlin Heidelberg, 1969), Vol. 4.
  69. J. N. Bahcall, Phys. Rev. 128, 1297 (1962).
  70. H. Brysk and M. E. Rose, Rev. Mod. Phys. 30, 1169 (1958).
  71. Q. Arnaud et al. (EDELWEISS Collaboration), Phys. Rev. Lett. 125, 141301 (2020).
  72. R. D. Lawson and M. Goeppert-Mayer, Phys. Rev. 117, 174 (1960).
  73. M. Honma, T. Otsuka, T. Mizusaki, and M. Hjorth-Jensen, Phys. Rev. C 80, 064323 (2009).
  74. B. Cheal et al., Phys. Rev. Lett. 104, 252502 (2010).
  75. A. Kanellakopoulos et al., Phys. Rev. C 102, 054331 (2020).
  76. L. C. Maximon and R. A. Schrack, J. Res. Natl. Bur. Stand., Sect. B 70, 85 (1966).
  77. M. Gorchtein and C. Y. Seng, Annu. Rev. Nucl. Part. Sci. 74, 23 (2024).
  78. C.-Y. Seng and M. Gorchtein, Phys. Rev. C 109, 045501 (2024).
  79. C.-Y. Seng, Phys. Rev. Lett. 130, 152501 (2023).
  80. J.-U. Nabi, M. Ishfaq, O. Niţescu, M. Mirea, and S. Stoica, Universe 6, 5 (2019).
  81. A. Ravlić, P. Schwerdtfeger, and W. Nazarewicz, Phys. Rev. C 111, 064323 (2025).

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Phys. Rev. Lett. 137, 131805– Published 24 September, 2026
  • Received 22 January 2026
  • Revised 29 May 2026
  • Accepted 31 July 2026
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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.

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