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arXiv 1509.05049hep-phhep-exhep-lat
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不稳定$b$介子的弱衰变

Weak decays of unstable $b$-mesons

Benjamín Grinstein, Jorge Martin Camalich

摘要:

我们研究了激发态$(b\bar q)$介子的衰变,作为$ΔB=1$弱跃迁短程结构的探针。这些状态在电磁或强相互作用下是不稳定的,尽管它们的宽度通常被相空间抑制。与赝标$B$介子相比,矢量$B^*$的纯轻子衰变没有手征抑制,并且对弱有效算符的不同组合敏感。一个有趣的例子是$B^*_s\to \ell^+\ell^-$,它的速率可以在标准模型中准确预测。分支分数是$\mathcal{B}\sim10^{-11}$,与轻子味无关,主要的不确定性来自于未测量的和理论上不为人所知的$B_s^*$宽度。我们讨论了在大型强子对撞机产生这种衰变模式的前景,并探讨了测量$B_s^*\to\ell\ell$振幅的可能性,而不是通过散射实验在$B_s^*$共振峰。最后,我们还讨论了充电电流$B_{u,c}^*\to\ellν$衰变,它可以提供补充信息的$b\to u\ellν$和$b\to c\ellν$的转变。

英文摘要:

We investigate the decays of the excited $(b\bar q)$ mesons as probes of the short-distance structure of the weak $ΔB=1$ transitions. These states are unstable under the electromagnetic or strong interactions although their widths are typically suppressed by phase space. As compared to the pseudoscalar $B$ meson, the purely leptonic decays of the vector $B^*$ are not chirally suppressed and are sensitive to different combinations of the underlying weak effective operators. An interesting example is $B^*_s\to \ell^+\ell^-$, which has a rate that can be accurately predicted in the standard model. The branching fraction is $\mathcal{B}\sim10^{-11}$, irrespective of the lepton flavor and where the main uncertainty stems from the unmeasured and theoretically not-well known $B_s^*$ width. We discuss the prospects for producing this decay mode at the LHC and explore the possibility of measuring the $B_s^*\to\ell\ell$ amplitude, instead, through scattering experiments at the $B_s^*$ resonance peak. Finally we also discuss the charged-current $B_{u,c}^*\to\ellν$ decay which can provide complementary information on the $b\to u\ellν$ and $b\to c\ellν$ transitions.

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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