arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2009.09313hep-lathep-exhep-ph
收藏

格点量子色动力学的$Λ_b \to Λ^*(1520)\ell^+\ell^-$形状因子

$Λ_b \to Λ^*(1520)\ell^+\ell^-$ form factors from lattice QCD

Stefan Meinel, Gumaro Rendon

备注：
28 pages, 9 figures
发表信息：
Phys. Rev. D 103, 074505 (2021)
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

我们提出了第一个格点量子色动力学确定的$Λ_b \to Λ^*(1520)$矢量，轴向矢量，和张量形状因子是相关的罕见的衰变$Λ_b \to Λ^*(1520)\ell^+\ell^-$。格点计算是在$Λ^*(1520)$静止坐标系中进行的，具有非零的$Λ_b$动量，并且仅限于高$q^2$区域。一个具有协变导数的插值场被用来获得与$Λ^*(1520)$的良好重叠。该分析将$Λ^*(1520)$视为稳定粒子，这有望成为这种窄共振的合理近似。对于轻夸克和奇异夸克使用畴壁作用量，而对于$b$夸克则使用各向异性的三叶草作用量，调整系数以产生正确的$B_s$动力学质量、静止质量和超精细分裂。我们使用三种不同的合奏的晶格规范场的配置所产生的RBC和UKQCD合作，并执行外推的形状因子的连续极限和物理π介子质量。我们给出了标准模型预测的$Λ_b \to Λ^*(1520)\ell^+\ell^-$微分分支分数和角度可观的高$q^2$区域。

英文摘要：

We present the first lattice QCD determination of the $Λ_b \to Λ^*(1520)$ vector, axial vector, and tensor form factors that are relevant for the rare decays $Λ_b \to Λ^*(1520)\ell^+\ell^-$. The lattice calculation is performed in the $Λ^*(1520)$ rest frame with nonzero $Λ_b$ momenta, and is limited to the high-$q^2$ region. An interpolating field with covariant derivatives is used to obtain good overlap with the $Λ^*(1520)$. The analysis treats the $Λ^*(1520)$ as a stable particle, which is expected to be a reasonable approximation for this narrow resonance. A domain-wall action is used for the light and strange quarks, while the $b$ quark is implemented with an anisotropic clover action with coefficients tuned to produce the correct $B_s$ kinetic mass, rest mass, and hyperfine splitting. We use three different ensembles of lattice gauge-field configurations generated by the RBC and UKQCD collaborations, and perform extrapolations of the form factors to the continuum limit and physical pion mass. We give Standard-Model predictions for the $Λ_b \to Λ^*(1520)\ell^+\ell^-$ differential branching fraction and angular observables in the high-$q^2$ region.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑