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arXiv 2108.07665hep-ex
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用ATLAS探测器寻找与τ轻子、$b$ -喷流和丢失横向动量的末态$pp$碰撞中的新现象

Search for new phenomena in $pp$ collisions in final states with tau leptons, $b$-jets, and missing transverse momentum with the ATLAS detector

ATLAS Collaboration

摘要:

在具有强子衰变τ轻子、$b$喷流和缺少横动量的末态中寻找新的现象。分析的数据集包括$pp$ ~碰撞数据,质心能量为$\sqrt s = 13$ TeV,积分亮度为139/fb,由大型强子对撞机提供,并在2015年至2018年期间使用ATLAS探测器记录。观测数据与预期的标准模型背景一致。在两种不同的情况下,在简化模型的结果进行解释。第一个模型是基于超对称性,并考虑对生产的顶部平方,其中每一个衰变成一个$b$ -夸克,中微子和τ slepton。每一个τ轻子依次衰变为一个τ轻子和一个几乎无质量的引力子。在这个模型中,顶夸克质量高达1.4 TeV可以排除在95%的置信水平在很宽的范围内的τ-slepton质量。第二个模型考虑了轻子和夸克衰变到第三代轻子和夸克的成对产生。根据分支分数带电轻子,leptoquark与质量约1.25 TeV可以排除在95%的置信水平的标量leptoquark的情况下,高达1.8 TeV(1.5 TeV)的矢量leptoquark在杨-米尔斯(最小耦合)的情况。此外,在超出标准模型的过程横截面上设置了与模型无关的上限。

英文摘要:

A search for new phenomena in final states with hadronically decaying tau leptons, $b$-jets, and missing transverse momentum is presented. The analyzed dataset comprises $pp$~collision data at a center-of-mass energy of $\sqrt s = 13$ TeV with an integrated luminosity of 139/fb, delivered by the Large Hadron Collider and recorded with the ATLAS detector from 2015 to 2018. The observed data are compatible with the expected Standard Model background. The results are interpreted in simplified models for two different scenarios. The first model is based on supersymmetry and considers pair production of top squarks, each of which decays into a $b$-quark, a neutrino and a tau slepton. Each tau slepton in turn decays into a tau lepton and a nearly massless gravitino. Within this model, top-squark masses up to 1.4 TeV can be excluded at the 95% confidence level over a wide range of tau-slepton masses. The second model considers pair production of leptoquarks with decays into third-generation leptons and quarks. Depending on the branching fraction into charged leptons, leptoquarks with masses up to around 1.25 TeV can be excluded at the 95% confidence level for the case of scalar leptoquarks and up to 1.8 TeV (1.5 TeV) for vector leptoquarks in a Yang--Mills (minimal-coupling) scenario. In addition, model-independent upper limits are set on the cross section of processes beyond the Standard Model.

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