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arXiv 1609.09078hep-phhep-ex
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$R_K$和$R_{D^{(*)}}$难题的同时解释:一个模型分析

Simultaneous Explanation of the $R_K$ and $R_{D^{(*)}}$ Puzzles: a Model Analysis

Bhubanjyoti Bhattacharya, Alakabha Datta, Jean-Pascal Guévin, David London, Ryoutaro Watanabe

摘要:

$R_K$和$R_{D^{(*)}}$是两个$B$ -衰变测量,目前表现出与SM的差异。最近,使用有效的场论方法,证明了一个新的物理模型可以同时解释$R_K$和$R_{D^{(*)}}$难题。有两种紫外完备化可以产生有效拉格朗日量:(i)$VB$:一种矢量玻色子,可以转化为$SU(2)_L$三重态,就像在SM中一样;(ii)$U_1$:一种$SU(2)_L$ -单重矢量轻夸克。在本文中,我们分别研究这些模型。一个关键点是,$VB$有助于$B^0_s$ - ${\bar B}^0_s$混合和$τ\to 3μ$,而$U_1$则没有。我们表明,当考虑到这些过程的约束,$VB$模型只是勉强可行。它预测了${\cal B} (τ^-\toμ^-μ^+μ^-) \simeq 2.1 \times 10^{-8}$。这在Belle II和LHCb是可测量的,因此构成$VB$的确凿信号。对于$U_1$,有几个观测值可能指向这个模型。也许最有趣的是轻子味违反衰变$Υ(3S) \to μτ$,这在以前的文献中被忽略了。$U_1$预测了${\cal B}(Υ(3S) \to μτ)|_{\rm max} = 8.0 \times 10^{-7}$。因此,如果观察到大的${\cal B}(Υ(3S) \to μτ)$值--这应该在Belle II可测量--将指示$U_1$模型。

英文摘要:

$R_K$ and $R_{D^{(*)}}$ are two $B$-decay measurements that presently exhibit discrepancies with the SM. Recently, using an effective field theory approach, it was demonstrated that a new-physics model can simultaneously explain both the $R_K$ and $R_{D^{(*)}}$ puzzles. There are two UV completions that can give rise to the effective Lagrangian: (i) $VB$: a vector boson that transforms as an $SU(2)_L$ triplet, as in the SM, (ii) $U_1$: an $SU(2)_L$-singlet vector leptoquark. In this paper, we examine these models individually. A key point is that $VB$ contributes to $B^0_s$-${\bar B}^0_s$ mixing and $τ\to 3μ$, while $U_1$ does not. We show that, when constraints from these processes are taken into account, the $VB$ model is just barely viable. It predicts ${\cal B} (τ^-\toμ^-μ^+μ^-) \simeq 2.1 \times 10^{-8}$. This is measurable at Belle II and LHCb, and therefore constitutes a smoking-gun signal of $VB$. For $U_1$, there are several observables that may point to this model. Perhaps the most interesting is the lepton-flavor-violating decay $Υ(3S) \to μτ$, which has previously been overlooked in the literature. $U_1$ predicts ${\cal B}(Υ(3S) \to μτ)|_{\rm max} = 8.0 \times 10^{-7}$. Thus, if a large value of ${\cal B}(Υ(3S) \to μτ)$ is observed -- and this should be measurable at Belle II -- the $U_1$ model would be indicated.

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。

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