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arXiv 1902.10077hep-ex
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用ATLAS探测器在$\sqrt{s} =13$ TeV上寻找$pp$碰撞中衰变成全强子末态顶夸克对的重粒子

Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV with the ATLAS detector

ATLAS Collaboration

摘要:

利用大型强子对撞机上ATLAS探测器在质量中心能量为$\sqrt{s} = $ 13 TeV对应于积分亮度为36.1 fb $^{-1}$的条件下记录的质子-质子碰撞数据,对衰变为一对顶夸克的新粒子进行了搜索。事件符合顶夸克对的生产和完全强子衰变模式的顶夸克的选择,需要多个高横向动量喷流,包括那些含有$b$ -强子。两种分析技术,利用专用顶夸克对重建在不同的运动学制度,用于优化搜索灵敏度,新的假设粒子在很宽的质量范围。不变的质量分布的两个重建的顶夸克候选人检查共振生产的新粒子具有不同的自旋和衰变宽度。与标准模型的预测没有明显的偏差,并且对新假设的$Z'$玻色子、暗物质介质、卡鲁扎-克莱因引力子和卡鲁扎-克莱因胶子的产生截面乘以分支分数设定了限制。通过与预测的产生截面的比较,顶色辅助的人工色模型中的$Z'$玻色子被排除的质量高达3.1 $-$ 3.6 TeV,在一个简化的框架中的暗物质介质被排除的质量范围从0.8 TeV到0.9 TeV和从2.0 TeV到2.2 TeV,和卡鲁扎-克莱因胶子被排除的质量高达3.4 TeV,这取决于粒子的衰变宽度。

英文摘要:

A search for new particles decaying into a pair of top quarks is performed using proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of $\sqrt{s} = $13 TeV corresponding to an integrated luminosity of 36.1 fb$^{-1}$. Events consistent with top-quark pair production and the fully hadronic decay mode of the top quarks are selected by requiring multiple high transverse momentum jets including those containing $b$-hadrons. Two analysis techniques, exploiting dedicated top-quark pair reconstruction in different kinematic regimes, are used to optimize the search sensitivity to new hypothetical particles over a wide mass range. The invariant mass distribution of the two reconstructed top-quark candidates is examined for resonant production of new particles with various spins and decay widths. No significant deviation from the Standard Model prediction is observed and limits are set on the production cross-section times branching fraction for new hypothetical $Z'$ bosons, dark-matter mediators, Kaluza-Klein gravitons and Kaluza-Klein gluons. By comparing with the predicted production cross-sections, the $Z'$ boson in the topcolor-assisted-technicolor model is excluded for masses up to 3.1$-$3.6 TeV, the dark-matter mediators in a simplified framework are excluded in the mass ranges from 0.8 TeV to 0.9 TeV and from 2.0 TeV to 2.2 TeV, and the Kaluza-Klein gluon is excluded for masses up to 3.4 TeV, depending on the decay widths of the particles.

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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