Nikhef Theory Group, Science Park 105, 1098 XG Amsterdam, Netherlands.
Phys Rev Lett. 2013 Aug 30;111(9):091802. doi: 10.1103/PhysRevLett.111.091802. Epub 2013 Aug 27.
Associated production of the Higgs boson with a top-antitop pair is a key channel to gather further information on the nature of the newly discovered boson at the LHC. Experimentally, however, its observation is very challenging due to the combination of small rates, difficult multijet final states, and overwhelming backgrounds. In the standard model, the largest number of events is expected when h→bb, giving rise to a W+ W- bbbb signature, deluged in tt + jets. A promising strategy to improve the sensitivity is to maximally exploit the theoretical information on the signal and background processes by means of the matrix element method. We show how, despite the complexity of the final state, the method can be efficiently applied to discriminate the signal against combinatorial and tt + jets backgrounds. Remarkably, we find that a moderate integrated luminosity in the next LHC run will be enough to make the signature involving both W's decaying leptonically as sensitive as the single-lepton one.
希格斯玻色子与顶夸克-反顶夸克对的联合产生是在 LHC 上进一步收集有关新发现玻色子性质信息的关键通道。然而，由于小的速率、困难的多喷注末态和压倒性的背景，其实验观测极具挑战性。在标准模型中，当 h→bb 时，预计会有最大数量的事件，导致 W+W-bbbb 特征，淹没在 tt+jets 中。提高灵敏度的一种很有前途的策略是通过矩阵元方法最大限度地利用信号和背景过程的理论信息。我们展示了尽管末态很复杂，但该方法可以有效地应用于区分信号与组合和 tt+jets 背景。值得注意的是，我们发现，在下一个 LHC 运行中，适度的积分亮度将足以使涉及两个 W 都通过轻子衰变的特征与单个轻子的特征一样敏感。
