Relativistic recoil as a key to the fine-structure puzzle in muonic $^{90}\text{Zr}$
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arXiv
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| Autori principali: | , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866909930577985536 |
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| author | Beyer, Konstantin A. Valuev, Igor A. Mandrykina, Zoia A. Sun, Zewen Oreshkina, Natalia S. |
| author_facet | Beyer, Konstantin A. Valuev, Igor A. Mandrykina, Zoia A. Sun, Zewen Oreshkina, Natalia S. |
| contents | The long-standing fine-structure anomaly in muonic $^{90}$Zr is resolved through a rigorous treatment of the relativistic-recoil effect. From a fit of ab initio QED calculations of the muonic $^{90}$Zr spectrum to precision measurements performed four decades ago, we extract a significantly more precise root-mean-square (rms) charge radius with 6-fold improvement in quality of the fit. A 2-parameter Fermi (2pF) distribution is assumed to model the nuclear charge density and yields a best-fit value of rms charge radius of $r_\text{rms}[^{90}\text{Zr}]=4.2732(7)$ fm ($χ^2 /{\text{DoF}} = 0.995$), in agreement with the previous muonic spectroscopy value, but a factor $6$ more precise, and 3$σ$ larger than the accepted literature value. Additionally, the same analysis has been performed for $^{120}$Sn, where the extracted value of $r_\text{rms}[^{120}\text{Sn}]=4.6518(34)$ fm ($χ^2 /{\text{DoF}} = 0.88$) is consistent with the accepted value. These results confirm our assumption that the muonic fine-structure puzzle arose from an incomplete treatment of QED effects and their uncertainties. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_22298 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Relativistic recoil as a key to the fine-structure puzzle in muonic $^{90}\text{Zr}$ Beyer, Konstantin A. Valuev, Igor A. Mandrykina, Zoia A. Sun, Zewen Oreshkina, Natalia S. Atomic Physics Nuclear Theory The long-standing fine-structure anomaly in muonic $^{90}$Zr is resolved through a rigorous treatment of the relativistic-recoil effect. From a fit of ab initio QED calculations of the muonic $^{90}$Zr spectrum to precision measurements performed four decades ago, we extract a significantly more precise root-mean-square (rms) charge radius with 6-fold improvement in quality of the fit. A 2-parameter Fermi (2pF) distribution is assumed to model the nuclear charge density and yields a best-fit value of rms charge radius of $r_\text{rms}[^{90}\text{Zr}]=4.2732(7)$ fm ($χ^2 /{\text{DoF}} = 0.995$), in agreement with the previous muonic spectroscopy value, but a factor $6$ more precise, and 3$σ$ larger than the accepted literature value. Additionally, the same analysis has been performed for $^{120}$Sn, where the extracted value of $r_\text{rms}[^{120}\text{Sn}]=4.6518(34)$ fm ($χ^2 /{\text{DoF}} = 0.88$) is consistent with the accepted value. These results confirm our assumption that the muonic fine-structure puzzle arose from an incomplete treatment of QED effects and their uncertainties. |
| title | Relativistic recoil as a key to the fine-structure puzzle in muonic $^{90}\text{Zr}$ |
| topic | Atomic Physics Nuclear Theory |
| url | https://arxiv.org/abs/2511.22298 |