标题： $Λ\to p \ell \barν_\ell$半轻子衰变的格点QCD研究 显示英文标题

标题： Study of the $Λ\to p \ell \barν_\ell$ semileptonic decay in lattice QCD

摘要： 我们首次确定了$\Lambda \to N$的矢量和轴矢量形式因子，这些是研究半轻子衰变$\Lambda \to p \ell \bar{\nu}_\ell$的重要输入。 此通道提供了一种干净且理论可控的方法，用于从重子领域提取CKM矩阵元$|V_{us}|$。 我们的分析使用了一个具有物理轻夸克、奇异夸克和魅夸克质量的规范系综，并得出了迄今为止最精确的全部转变形式因子的确定结果——包括第二类贡献——以及相关的耦合、半径以及缪子与电子衰变率的比值，这一可观测量对可能的非标准标量和张量相互作用非常敏感。 我们将非微扰的结果与小参数$\delta = (m_\Lambda - m_N)/m_\Lambda \approx 0.16$的下一阶下一阶展开进行了比较。 我们发现，忽略形式因子的$q^2$依赖性的常见现象学近似会导致衰变率出现$\sim 4\%$的偏差。 这强调了精确的完全非微扰形式因子输入对于实现未来实验计划的百分之一以下精度目标的关键重要性。 显示英文摘要

摘要： We present the first lattice QCD determination of the $\Lambda \to N$ vector and axial-vector form factors, which are essential inputs for studying the semileptonic decay $\Lambda \to p \ell \bar{\nu}_\ell$. This channel provides a clean, theoretically controlled avenue for extracting the CKM matrix element $|V_{us}|$ from the baryon sector. Our analysis uses a gauge ensemble with physical light, strange, and charm quark masses and yields the most precise determination to date of the full set of transition form factors -- including second-class contributions -- as well as the associated couplings, radii, and the ratio of muon-to-electron decay rates, an observable sensitive to possible non-standard scalar and tensor interactions. We compare our non-perturbative results with next-to-next-to-leading order expansions in the small parameter $\delta = (m_\Lambda - m_N)/m_\Lambda \approx 0.16$. We find that the common phenomenological approximation of neglecting the $q^2$-dependence of the form factors leads to a $\sim 4\%$ deviation in the decay rate. This underscores the critical importance of precise, fully non-perturbative form factor inputs for achieving the sub-percent precision targets of upcoming experimental programs.