标题： 探测翻转两Higgs双重模型中的低质量伪标量 显示英文标题

标题： Probing the low mass pseudoscalar in flipped Two Higgs Doublet Model

摘要： 翻转两Higgs双重态模型（2HDM）的唯象学研究到目前为止相对较少，与其它更常讨论的类型相比更是如此。 研究发现，这一情景和其他几种情景一样，允许存在一个轻质量的中性赝标量粒子$A$，其质量范围在20至60 GeV之间，且与当前所有实验数据和理论限制一致。 然而，这个赝标量粒子几乎完全衰变为$b\bar{b}$对的事实，使得它在大型强子对撞机（LHC）上的识别成为一个具有挑战性的任务。 在确定翻转2HDM参数空间中产生轻质赝标量的区域后，我们在过程$pp \rightarrow A Z(Z^{*}) \rightarrow b\bar{b} \ell^+ \ell^-$中识别出一个有用的搜索通道。 基于切割分析，继而使用基于Boosted Decision Trees的方法分析表明，即使考虑系统不确定性，翻转2HDM中的轻质$A$情景在高亮度LHC运行中应该能够以相当高的统计显著性被检测到。 此外，参数空间的某些部分，特别是在$m_A = 30 - 40$GeV 附近，在Run-2期间本身就有望达到发现水平的探测能力。 显示英文摘要

摘要： The phenomenology of the flipped two-Higgs-doublet model (2HDM) is relatively less explored so far, as compared to the other, commonly discussed, types. It is found that this scenario, like several others, admits of a light neutral pseudoscalar $A$ in the mass range 20 - 60 GeV, consistently with all current experimental data and theoretical constraints. However, the fact that such a pseudoscalar decays overwhelmingly into a $b\bar{b}$ pair makes its identification at the Large Hadron Collider (LHC) a challenging task. After identifying the region of the flipped 2HDM parameter space yielding a light pseudoscalar, we identify a useful search channel in the process $pp \rightarrow A Z(Z^{*}) \rightarrow b\bar{b} \ell^+ \ell^-$. A cut-based analysis, followed by one based on Boosted Decision Trees, shows that the light-$A$ scenario in flipped 2HDM should be detectable with rather high statistical significance at the high-luminosity LHC run, even after including systematic uncertainties. Furthermore, part of the parameter space, especially around $m_A = 30 - 40$ GeV is amenable to detection at the discovery level within Run-2 itself.