$b\to sν\barν$ 中重子-介子求和规则端点结构分析
Endpoint anatomy of the baryon--meson sum rule in $b\to sν\barν$
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中文总结 AI 辅助
本文研究 $b\to sν\barν$ 系统中重子-介子求和规则的来源，发现其系数在最大反冲点约为 1/2，零反冲点精确为零，积分后接近 1/4，但并非局域对称性系数，为更广泛重到轻衰变求和规则构建提供指导。
中文摘要 AI 辅助
重子-介子求和规则使得纯介子与重子测量之间可以进行交叉检验。与重到重跃迁中的对应关系不同，类似的重到轻关系缺乏明确的重夸克对称性来源。我们通过研究两个运动学端点处的相关螺旋度振幅，探究其在 $b\to s\nu\bar\nu$ 系统中的来源。尽管求和规则可由简单的短距离结构代数推导得出，但其系数非平凡地依赖于强子动力学。在最大反冲点，子重子 ${\cal B}=\Lambda,\Xi$ 的系数在当前形状因子不确定性范围内与近似值 $1/2$ 一致。相反，在零反冲点，运动学螺旋度投影强制其精确为零。完全积分后的系数数值上接近 $1/4$。然而，与重到重系统中四分之一系数不同，它们并非局域对称性系数，而是由两个端点之间行为塑造的积分量。这一理解可能为更一般的重到轻衰变中重子-介子求和规则的构建提供指导。
英文摘要
Baryon-meson sum rules enable cross-checks among exclusive mesonic and baryonic measurements. Unlike their heavy-to-heavy counterparts, analogous heavy-to-light relations lack an explicit heavy-quark-symmetry origin. We investigate their origin in the $b\to sν\barν$ system by studying the relevant helicity amplitudes at the two kinematic endpoints. Although the sum rule follows algebraically from the simple short-distance structure, its coefficient depends nontrivially on the hadronic dynamics. At maximum recoil, the coefficient for the daughter baryons ${\cal B}=Λ,Ξ$ is consistent with the approximate value $1/2$ within current form-factor uncertainties. At zero recoil, by contrast, a kinematic helicity projection enforces its exact vanishing. The fully integrated coefficients are numerically close to $1/4$. However, unlike the one-quarter coefficient in the heavy-to-heavy system, they are not local symmetry coefficients but integrated quantities shaped by the behavior between the two endpoints. This understanding may guide the construction of baryon-meson sum rules in more general heavy-to-light decays.
发表机构
- Institute for Advanced Research, Nagoya University（名古屋大学先进研究院）
- Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University（名古屋大学小林-益川粒子宇宙起源研究所）
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