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arXiv 1806.07403hep-phhep-ex
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$b \to s μ^+ μ^-$和$b \to c τ^- {\barν}$异常的组合解释:一个通用模型分析

Combined Explanations of the $b \to s μ^+ μ^-$ and $b \to c τ^- {\barν}$ Anomalies: a General Model Analysis

Jacky Kumar, David London, Ryoutaro Watanabe

摘要:

有四种树级新物理学(NP)模型可以潜在地同时解释$b \to s μ^+ μ^-$和$b \to c τ^- {\barν}$异常。它们是S3,U3和U1轻夸克(LQs),以及一个三重的SM-样矢量玻色子(VB)。在NP主要耦合到第三代的理论假设下,以前的分析发现,当考虑到其他过程的约束时,S3,U3和VB模型不能解释B异常,但U1是可行的。在本文中,我们重新分析这些模型,但没有任何假设,他们的耦合。我们发现,即使在这种最一般的情况下,S3和U3也被排除在外。对于U1模型,半轻子味违反过程$B \to K^{(*)} μ^\pm τ^\mp$,$τ\to μϕ$和$Υ\to μτ$的约束是非常重要的,而这些约束在很大程度上被忽略了.由于LFV约束,U1 LQ的耦合模式类似于用上述理论假设获得的模式。此外,LFV约束使得使用重整化群方程获得的那些约束不重要。至于VB模型,如果由于来自${\bar B}^0_s$混合、$τ\to 3μ$和$τ\to μν{\barν}$的附加约束而做出上述理论假设,则将其排除。相比之下,我们发现了一组不同的NP耦合,既解释了$b \to s μ^+ μ^-$异常,是兼容的所有约束。然而,它不能再现$b \to c τ^- {\barν}$异常的测量值--只有当未来的测量发现这些异常的中心值减小时,它才是可行的。即便如此,这个VB模型被排除在大质量共振双μ子对的LHC边界之外。这个结论是在没有任何关于NP耦合的假设的情况下得出的。

英文摘要:

There are four models of tree-level new physics (NP) that can potentially simultaneously explain the $b \to s μ^+ μ^-$ and $b \to c τ^- {\barν}$ anomalies. They are the S3, U3 and U1 leptoquarks (LQs), and a triplet of SM-like vector bosons (VBs). Under the theoretical assumption that the NP couples predominantly to the third generation, previous analyses found that, when constraints from other processes are taken into account, the S3, U3 and VB models cannot explain the B anomalies, but U1 is viable. In this paper, we reanalyze these models, but without any assumption about their couplings. We find that, even in this most general case, S3 and U3 are excluded. For the U1 model, constraints from the semileptonic lepton-flavour-violating (LFV) processes $B \to K^{(*)} μ^\pm τ^\mp$, $τ\to μϕ$ and $Υ\to μτ$, which have been largely ignored previously, are found to be very important. Because of the LFV constraints, the pattern of couplings of the U1 LQ is similar to that obtained with the above theoretical assumption. Also, the LFV constraints render unimportant those constraints obtained using the renormalization group equations. As for the VB model, it is excluded if the above theoretical assumption is made due to the additional constraints from $B^0_s$-${\bar B}^0_s$ mixing, $τ\to 3μ$ and $τ\to μν{\barν}$. By contrast, we find a different set of NP couplings that both explains the $b \to s μ^+ μ^-$ anomaly and is compatible with all constraints. However, it does not reproduce the measured values of the $b \to c τ^- {\barν}$ anomalies -- it would be viable only if future measurements find that the central values of these anomalies are reduced. Even so, this VB model is excluded by the LHC bounds on high-mass resonant dimuon pairs. This conclusion is reached without any assumptions about the NP couplings.

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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