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在LHC对$b \to c τν$异常的非共振新物理研究

Non-resonant new physics search at the LHC for the $b \to c τν$ anomalies

Motoi Endo, Syuhei Iguro, Teppei Kitahara, Michihisa Takeuchi, Ryoutaro Watanabe

备注：
39 pages, 9 figures, 14 tables. Ancillary files are available, JHEP published version
发表信息：
Journal reference: JHEP 02 (2022) 106
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摘要：

受$b \to c τ\overlineν$异常的启发，我们研究了在大型强子对撞机（LHC）上通过考虑具有高能强子衰变的$τ$轻子、$b$喷流和大的丢失横动量（$pp \to τ_h \overline{b} + E_{\rm T}^{\rm miss}$）的末态来寻找新物理的非共振过程.这样的搜索对于探索对$b \to c τ\overlineν$的新物理贡献是有用的。它们不仅在六维有效场论（EFT）中进行了分析，而且在显式的LQ非解耦LQ模型中进行了分析。前者是通过在后者中取大LQ质量的极限来实现的。澄清了即使在寻找$pp \to τ_h \overline{b} + E_{\rm T}^{\rm miss}$时，LHC灵敏度对$O(1)$ TeV的LQ质量也是敏感的。虽然LQ模型提供了比EFT极限更弱的灵敏度，但是发现在整个LQ质量区域中，与传统的单$τ$搜索（$pp \to τ_h + E_{\rm T}^{\rm miss}$）相比，$pp \to τ_h \overline{b} + E_{\rm T}^{\rm miss}$的非共振搜索可以提高$\approx 40\%$的灵敏度。因此，预计$b \to c τ\overlineν$异常所建议的大多数参数区域可以在HL-LHC上探测到。此外，它表明，$\text{R}_2$ LQ方案是完全可访问的，一旦LHC运行2的数据进行分析。此外，我们讨论了$τ_h$的电荷选择以进一步抑制标准模型背景，并研究了$b,\, τ$之间的角相关性和缺失的横向动量以区分LQ场景。

英文摘要：

Motivated by the $b \to c τ\overlineν$ anomalies, we study non-resonant searches for new physics at the large hadron collider (LHC) by considering final states with an energetic and hadronically decaying $τ$ lepton, a $b$-jet and large missing transverse momentum ($pp \to τ_h \overline{b} + E_{\rm T}^{\rm miss}$). Such searches can be useful to probe new physics contributions to $b \to c τ\overlineν$. They are analyzed not only within the dimension-six effective field theory (EFT) but also in explicit leptoquark (LQ) models with the LQ non-decoupled. The former is realized by taking a limit of large LQ mass in the latter. It is clarified that the LHC sensitivity is sensitive to the LQ mass for $O(1)$ TeV even in the search of $pp \to τ_h \overline{b} + E_{\rm T}^{\rm miss}$. Although the LQ models provide a weaker sensitivity than the EFT limit, it is found that the non-resonant search of $pp \to τ_h \overline{b} + E_{\rm T}^{\rm miss}$ can improve the sensitivity by $\approx 40\%$ versus a conventional mono-$τ$ search ($pp \to τ_h + E_{\rm T}^{\rm miss}$) in the whole LQ mass region. Consequently, it is expected that most of the parameter regions suggested by the $b \to c τ\overlineν$ anomalies can be probed at the HL-LHC. Also, it is shown that $\text{R}_2$ LQ scenario is accessible entirely once the LHC Run 2 data are analyzed. In addition, we discuss a charge selection of $τ_h$ to further suppress the standard-model background, and investigate the angular correlations among $b,\, τ$ and the missing transverse momentum to discriminate the LQ scenarios.

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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