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arXiv 1503.05066hep-ex
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用ATLAS探测器寻找在$\sqrt{s}$ = 8 TeV的pp碰撞中与顶夸克结合产生并衰变为$b\bar{b}$的标准模型希格斯玻色子

Search for the Standard Model Higgs boson produced in association with top quarks and decaying into $b\bar{b}$ in pp collisions at $\sqrt{s}$ = 8 TeV with the ATLAS detector

ATLAS Collaboration

摘要:

本文提出了一种寻找与一对顶夸克$t\bar{t}H$相伴产生的标准模型希格斯玻色子的方法。分析使用20.3 fb $^{-1}$的pp碰撞数据在$\sqrt{s}$ = 8 TeV,收集与ATLAS探测器在大型强子对撞机在2012年。搜索是针对H到$b\bar{b}$的衰变模式设计的,并使用包含一个或两个电子或μ子的事件。为了提高搜索的灵敏度,根据它们的喷射和b标记的喷射多样性对事件进行分类。神经网络用于区分信号和背景事件,后者由$t\bar{t}$ +喷流生产主导。在单轻子通道中,使用矩阵元素方法计算的变量被包括作为神经网络的输入,以提高不可约$t\bar{t}$ + $b\bar{b}$背景的辨别力。未发现显著超出背景预期的事件,并且在95%置信水平下获得了标准模型横截面的3.4(2.2)倍的观察(预期)限值。假设希格斯玻色子质量为125 GeV,测得的$t\bar{t}H$信号横截面与标准模型期望值的比值为$μ$ = 1.5 $\pm$ 1.1。

英文摘要:

A search for the Standard Model Higgs boson produced in association with a pair of top quarks, $t\bar{t}H$, is presented. The analysis uses 20.3 fb$^{-1}$ of pp collision data at $\sqrt{s}$ = 8 TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the H to $b\bar{b}$ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by $t\bar{t}$+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible $t\bar{t}$+$b\bar{b}$ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95% confidence level. The ratio of the measured $t\bar{t}H$ signal cross section to the Standard Model expectation is found to be $μ$ = 1.5 $\pm$ 1.1 assuming a Higgs boson mass of 125 GeV.

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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