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arXiv 2001.06375hep-ph
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用轻锋方法综合分析二重重子弱跃迁形状因子

A comprehensive analysis of weak transition form factors for doubly heavy baryons in the light front approach

Xiao-Hui Hu, Run-Hui Li, Zhi-Peng Xing

摘要:

在光锋夸克模型下,系统地研究了带电流和味变中性流诱导的二重重子到自旋$1/2$或自旋$3/2$基态重子跃迁的形状因子.在跃迁中,两个旁观夸克有两种自旋组态,这两种组态都在计算中考虑。我们使用了一个新的顶点函数,并受味SU(3)对称性的启发,我们还提供了一种新的方法来推导味自旋因子。利用得到的跃迁形状因子,我们对$c\to d/s \ell^+ν$,$b\to c/u\ell^-\bar ν$和$b\to d/s\ell^+\ell^-$诱导的重子半轻子衰变进行了唯象研究.给出了部分衰减宽度、分支比和极化比$Γ_{L}/Γ_{T}$ s的计算结果。我们发现由$c\to d,s$跃迁引起的半轻子衰变的分支比大多数在$10^{-3}\sim10^{-2}$量级,这对寻找其他的重子可能是有用的。在形状因子的基础上,讨论了味SU(3)对称性和对称性破缺效应的来源。我们发现,在粲化重子衰变中,SU(3)对称性破缺效应可能是相当大的,而在底态情况下,SU(3)对称性破缺效应不太显著。我们的研究结果可以在未来的实验设施进行检查。

英文摘要:

The transition form factors for doubly heavy baryons into a spin-$1/2$ or spin-$3/2$ ground-state baryon induced by both the charged current and the flavor changing neutral current are systematically studied within the light-front quark model. In the transition the two spectator quarks have two spin configurations and both are considered in this calculation. We use an updated vertex functions, and inspired by the flavor SU(3) symmetry, we also provide a new approach to derive the flavor-spin factors. With the obtained transition form factors, we perform a phenomenological study of the corresponding semi-leptonic decays of doubly heavy baryons induced by the $c\to d/s \ell^+ν$, $b\to c/u\ell^-\bar ν$ and $b\to d/s\ell^+\ell^-$. Results for partial decay widths, branching ratios and the polarization ratios $Γ_{L}/Γ_{T}$s are given. We find that most branching ratios for the semi-leptonic decays induced by the $c\to d,s$ transitions are at the order of $10^{-3}\sim10^{-2}$, which might be useful for the search of other doubly-heavy baryons. Uncertainties in form factors, the flavor SU(3) symmetry and sources of symmetry breaking effects are discussed. We find that the SU(3) symmetry breaking effects could be sizable in charmed baryon decays while in the bottomed case, the SU(3) symmetry breaking effects are less significant. Our results can be examined at the experimental facilities in the future.

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