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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| Soggetti: | |
| Accesso online: | https://arxiv.org/abs/2504.08711 |
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| _version_ | 1866914316628787200 |
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| author | Brase, C. Miyagi, T. Menéndez, J. Schwenk, A. |
| author_facet | Brase, C. Miyagi, T. Menéndez, J. Schwenk, A. |
| contents | We explore the impact of two-body currents (2BCs) at finite momentum transfer with a focus on magnetic dipole properties in $^{48}$Ca and $^{48}$Ti. To this end, we derive a multipole decomposition of 2BCs to fully include the momentum-transfer dependence in $\mathit{ab\,initio}$ calculations. As application, we investigate the effects of 2BCs on the strong M1 transition at 10.23$\,$MeV in $^{48}$Ca using the valence-space in-medium similarity renormalization group (VS-IMSRG) with a set of non-implausible interactions as well as the 1.8/2.0 (EM) interaction. Experiments, such as $(e,e')$ and $(γ,n)$, disagree on the magnetic dipole strength $B$(M1) for this transition. Our VS-IMSRG results favor larger $B$(M1) values similar to recent coupled-cluster calculations. However, for this transition there are larger cancellations between the leading pion-in-flight and seagull 2BCs, so that future calculations including higher-order 2BCs are important. For validation of our results, we investigate additional observables in $^{48}$Ca as well as M1 transitions in $^{48}$Ti. For these, our results agree with experiment. Finally, our results show that for medium-mass nuclei 2BC contributions to M1 and Gamow-Teller transitions are, as expected, very different. Therefore, using similar quenching factors for both in phenomenological calculations is not supported from first principles. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_08711 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Two-body currents at finite momentum transfer and applications to M1 transitions Brase, C. Miyagi, T. Menéndez, J. Schwenk, A. Nuclear Theory We explore the impact of two-body currents (2BCs) at finite momentum transfer with a focus on magnetic dipole properties in $^{48}$Ca and $^{48}$Ti. To this end, we derive a multipole decomposition of 2BCs to fully include the momentum-transfer dependence in $\mathit{ab\,initio}$ calculations. As application, we investigate the effects of 2BCs on the strong M1 transition at 10.23$\,$MeV in $^{48}$Ca using the valence-space in-medium similarity renormalization group (VS-IMSRG) with a set of non-implausible interactions as well as the 1.8/2.0 (EM) interaction. Experiments, such as $(e,e')$ and $(γ,n)$, disagree on the magnetic dipole strength $B$(M1) for this transition. Our VS-IMSRG results favor larger $B$(M1) values similar to recent coupled-cluster calculations. However, for this transition there are larger cancellations between the leading pion-in-flight and seagull 2BCs, so that future calculations including higher-order 2BCs are important. For validation of our results, we investigate additional observables in $^{48}$Ca as well as M1 transitions in $^{48}$Ti. For these, our results agree with experiment. Finally, our results show that for medium-mass nuclei 2BC contributions to M1 and Gamow-Teller transitions are, as expected, very different. Therefore, using similar quenching factors for both in phenomenological calculations is not supported from first principles. |
| title | Two-body currents at finite momentum transfer and applications to M1 transitions |
| topic | Nuclear Theory |
| url | https://arxiv.org/abs/2504.08711 |