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Signatures of a flavor changing Z′ boson in Bq → γZ′
Nuclear Physics B ( IF 2.8 ) Pub Date : 2020-11-12 , DOI: 10.1016/j.nuclphysb.2020.115237
Shao-Long Chen , Amit Dutta Banik , Zhaofeng Kang , Qin Qin , Yoshihiro Shigekami

Rare B meson decays offer an opportunity to probe a light hidden Z boson. In this work we explore a new channel BqγZ (q=d,s) followed by a cascade decay of Z into an invisible (neutrino or dark matter) or charged lepton pair + (=e,μ). The study is based on a simplified effective model where the down quark sector has tiny flavor-changing neutral current couplings with Z. For the first time, we calculate BR(BqγZ) at the leading power of 1/mb and 1/Eγ. Confronting with the strong constraints from semi-invisible decays of B meson, we find that the branching ratio for Bdinvisible+γ can be larger than its Standard Model background prediction, leaving a large room for new physics, in particular for light dark matter. Additionally, the branching ratio for Bde+eγ can also be sizable when the corresponding flavor violating Z coupling to quarks is of the axial-vector type. On the other hand, the predicted branching ratios of Bdμ+μγ and Bs+γ are severely constrained by the experimental measurements.



中文翻译:

B q  →  γZ '中的Z '玻色子的风味变化特征

罕见的B介子衰变提供了探测暗光的机会ž玻色子。在这项工作中,我们探索了一个新的渠道qγžq=ds),然后是 ž 变成看不见的(中微子或暗物质)或带电的轻子对 +-=Ëμ)。这项研究基于简化的有效模型,在该模型中,下夸克区具有微小的变味中性电流耦合,ž。我们第一次计算BRqγž 在...的领导力 1个/b1个/Ëγ。面对B介子的半隐形衰变的强约束,我们发现d无形+γ可以比标准模型的背景预测大,这为新物理,尤其是浅暗物质留有很大的空间。此外,dË+Ë-γ 当违反相应的风味时,也可以调整大小 ž与夸克的耦合是轴向矢量类型。另一方面,预测的分支比为dμ+μ-γs+-γ 受到实验测量的严格限制。

更新日期:2020-11-18
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