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| Main Authors: | , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2511.05189 |
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| _version_ | 1866915803012530176 |
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| author | Sunaga, Ayaki Fleig, Timo |
| author_facet | Sunaga, Ayaki Fleig, Timo |
| contents | Diatomic molecules with an energetically low-lying $^3 Δ_1$ state are attractive platforms to detect new physics beyond the Standard Model, such as parity- and time-reversal violating phenomena. One of the advantages of using a $^3 Δ_1$ state is its tiny $Λ$-splitting due to the coupling between the electronic and rotational angular momenta, which facilitates polarizing the molecules in small external electric fields. Theoretical estimation of the magnitude of the $Λ$-splitting is helpful for planning new experiments. In this study, we present a theoretical model to calculate the $Λ$-splitting. Our model integrates the relativistic four-component wavefunction and the traditional rotational Hamiltonian based on Hund's case (a). The multireference character of the wavefunction is taken into account. Our calculations for PtH and ThF$^+$ molecules qualitatively agree with experiment. The $Λ$-splitting of TaO$^+$ for the rotational ground state is predicted to be around 9 kHz. This tiny splitting can reduce the systematic uncertainty, but in a practical experiment, it may cause depolarization during rotation ramp-up. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_05189 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Rotational Splittings in Diatomic Molecules of Interest to Searches for New Physics Sunaga, Ayaki Fleig, Timo Atomic Physics Diatomic molecules with an energetically low-lying $^3 Δ_1$ state are attractive platforms to detect new physics beyond the Standard Model, such as parity- and time-reversal violating phenomena. One of the advantages of using a $^3 Δ_1$ state is its tiny $Λ$-splitting due to the coupling between the electronic and rotational angular momenta, which facilitates polarizing the molecules in small external electric fields. Theoretical estimation of the magnitude of the $Λ$-splitting is helpful for planning new experiments. In this study, we present a theoretical model to calculate the $Λ$-splitting. Our model integrates the relativistic four-component wavefunction and the traditional rotational Hamiltonian based on Hund's case (a). The multireference character of the wavefunction is taken into account. Our calculations for PtH and ThF$^+$ molecules qualitatively agree with experiment. The $Λ$-splitting of TaO$^+$ for the rotational ground state is predicted to be around 9 kHz. This tiny splitting can reduce the systematic uncertainty, but in a practical experiment, it may cause depolarization during rotation ramp-up. |
| title | Rotational Splittings in Diatomic Molecules of Interest to Searches for New Physics |
| topic | Atomic Physics |
| url | https://arxiv.org/abs/2511.05189 |