SCET sum rules for $Λ_b \to Λ\ell^+\ell^-$, $Λγ$ decays
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| Auteurs principaux: | , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866911031488413696 |
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| author | Lu, Long-Shun Lü, Cai-Dian Shen, Yue-Long Wei, Yan-Bing |
| author_facet | Lu, Long-Shun Lü, Cai-Dian Shen, Yue-Long Wei, Yan-Bing |
| contents | We construct light-cone sum rules for various types of effective form factors in the $Λ_b \to Λ\ell^+\ell^-$ and $Λ_b \to Λγ$ decays by analyzing vacuum-to-$Λ_b$ (or $γ^\ast$-to-$Λ_b$) correlation functions with the light $Λ$-baryon interpolating current. These form factors, defined via hadronic matrix elements within soft-collinear effective theory (SCET), enter the next-to-leading-power QCD factorization formulas for large-recoil transitions. Implementing the perturbative matching from $\text{SCET}_\text{I}$ to heavy quark effective theory, we determine the hard-collinear functions at next-to-leading-order accuracy. Based on light-cone sum rule predictions for the $Λ_b \to Λ$ form factors, we compute the $q^2$-dependent differential branching fraction, forward-backward asymmetry and dilepton longitudinal polarization fraction for $Λ_b \to Λ\ell^+\ell^-$ decay, as well as the branching fraction for $Λ_b \to Λγ$ decay. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_21419 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | SCET sum rules for $Λ_b \to Λ\ell^+\ell^-$, $Λγ$ decays Lu, Long-Shun Lü, Cai-Dian Shen, Yue-Long Wei, Yan-Bing High Energy Physics - Phenomenology We construct light-cone sum rules for various types of effective form factors in the $Λ_b \to Λ\ell^+\ell^-$ and $Λ_b \to Λγ$ decays by analyzing vacuum-to-$Λ_b$ (or $γ^\ast$-to-$Λ_b$) correlation functions with the light $Λ$-baryon interpolating current. These form factors, defined via hadronic matrix elements within soft-collinear effective theory (SCET), enter the next-to-leading-power QCD factorization formulas for large-recoil transitions. Implementing the perturbative matching from $\text{SCET}_\text{I}$ to heavy quark effective theory, we determine the hard-collinear functions at next-to-leading-order accuracy. Based on light-cone sum rule predictions for the $Λ_b \to Λ$ form factors, we compute the $q^2$-dependent differential branching fraction, forward-backward asymmetry and dilepton longitudinal polarization fraction for $Λ_b \to Λ\ell^+\ell^-$ decay, as well as the branching fraction for $Λ_b \to Λγ$ decay. |
| title | SCET sum rules for $Λ_b \to Λ\ell^+\ell^-$, $Λγ$ decays |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2506.21419 |