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<p>We construct light-cone sum rules for various types of effective form factors in the Λ<sub><i>b</i></sub> → Λ<i>ℓ</i><sup>+</sup><i>ℓ</i><sup><i>−</i></sup> and Λ<sub><i>b</i></sub> → Λ<i>γ</i> decays by analyzing vacuum-to-Λ<sub><i>b</i></sub> (or <i>γ</i><sup>*</sup>-to-Λ<sub><i>b</i></sub>) 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 SCET<sub>I</sub> 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<sub><i>b</i></sub> → Λ form factors, we compute the <i>q</i><sup>2</sup>-dependent differential branching fraction, forward-backward asymmetry and dilepton longitudinal polarization fraction for Λ<sub><i>b</i></sub> → Λ<i>ℓ</i><sup>+</sup><i>ℓ</i><sup><i>−</i></sup> decay, as well as the branching fraction for Λ<sub><i>b</i></sub> → Λ<i>γ</i> decay.</p>

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SCET sum rules for Λb → Λℓ+ℓ−, Λγ decays

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年9月23日

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  • Long-Shun Lu,
  • Cai-Dian Lü,
  • Yue-Long Shen,
  • Yan-Bing Wei

摘要

We construct light-cone sum rules for various types of effective form factors in the Λb → Λℓ+ℓ− and Λb → Λγ decays by analyzing vacuum-to-Λb (or γ*-to-Λb) 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 SCETI 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 Λb → Λ form factors, we compute the q2-dependent differential branching fraction, forward-backward asymmetry and dilepton longitudinal polarization fraction for Λb → Λℓ+ℓ− decay, as well as the branching fraction for Λb → Λγ decay.