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| Main Authors: | , , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2604.25673 |
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| _version_ | 1866914514405949440 |
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| author | Bai, Yu-Xuan Hao, Jin Guo, Zhi-Hui |
| author_facet | Bai, Yu-Xuan Hao, Jin Guo, Zhi-Hui |
| contents | In this work we explore the semileptonic $τ$ decays into the axion-like particle ($a$)-meson final states within chiral effective field theory. The next-to-leading-order mixing matrix for the $π^0$-$η$-$η'$-$a$ system with the linear isospin-breaking effects, is exploited and then implemented to calculate the hadronic form factors relevant to the $τ$ decays. The resonance parameters entering the form factors are determined from fits to the experimental spectra of $τ^- \to π^- π^0 ν_τ$, $τ^- \to K_S π^- ν_τ$, and $τ^- \to K^- ην_τ$. We then focus on the predictions to the branching ratios, invariant-mass distributions, and forward-backward asymmetries from the $τ^-\to P a ν_τ$ processes, with $P=π^-$ and $K^-$. Our results provide a quantitative basis for future searches of the axion-like particle signals in semileptonic $τ$ decays. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_25673 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Axion-like particle-meson production in semileptonic $τ$ decays Bai, Yu-Xuan Hao, Jin Guo, Zhi-Hui High Energy Physics - Phenomenology In this work we explore the semileptonic $τ$ decays into the axion-like particle ($a$)-meson final states within chiral effective field theory. The next-to-leading-order mixing matrix for the $π^0$-$η$-$η'$-$a$ system with the linear isospin-breaking effects, is exploited and then implemented to calculate the hadronic form factors relevant to the $τ$ decays. The resonance parameters entering the form factors are determined from fits to the experimental spectra of $τ^- \to π^- π^0 ν_τ$, $τ^- \to K_S π^- ν_τ$, and $τ^- \to K^- ην_τ$. We then focus on the predictions to the branching ratios, invariant-mass distributions, and forward-backward asymmetries from the $τ^-\to P a ν_τ$ processes, with $P=π^-$ and $K^-$. Our results provide a quantitative basis for future searches of the axion-like particle signals in semileptonic $τ$ decays. |
| title | Axion-like particle-meson production in semileptonic $τ$ decays |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2604.25673 |