A possible solution to the gallium anomaly moving beyond the leptonic wave function factorization
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866908774854295552 |
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| author | Cadeddu, M. Cargioli, N. Dordei, F. Ferro, L. Giunti, C. Pitzalis, M. |
| author_facet | Cadeddu, M. Cargioli, N. Dordei, F. Ferro, L. Giunti, C. Pitzalis, M. |
| contents | For over thirty years, a $\sim20\%$ deficit, now exceeding $5σ$, has persisted between measured and predicted neutrino capture rates on $^{71}$Ga, as observed in radioactive source experiments (namely GALLEX, SAGE, and more recently BEST) using $^{51}$Cr and $^{37}$Ar. 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 work, 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 $^{71}{\textrm{Ge}}$, we find that the revised cross-section can be significantly reduced, potentially resolving the gallium anomaly without invoking new physics. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_20560 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | A possible solution to the gallium anomaly moving beyond the leptonic wave function factorization Cadeddu, M. Cargioli, N. Dordei, F. Ferro, L. Giunti, C. Pitzalis, M. High Energy Physics - Phenomenology High Energy Physics - Experiment Nuclear Experiment Nuclear Theory For over thirty years, a $\sim20\%$ deficit, now exceeding $5σ$, has persisted between measured and predicted neutrino capture rates on $^{71}$Ga, as observed in radioactive source experiments (namely GALLEX, SAGE, and more recently BEST) using $^{51}$Cr and $^{37}$Ar. 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 work, 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 $^{71}{\textrm{Ge}}$, we find that the revised cross-section can be significantly reduced, potentially resolving the gallium anomaly without invoking new physics. |
| title | A possible solution to the gallium anomaly moving beyond the leptonic wave function factorization |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment Nuclear Experiment Nuclear Theory |
| url | https://arxiv.org/abs/2512.20560 |