AI 中文总结
该研究在质子-质子碰撞中，通过四分支大半径喷注特征搜索与初态辐射喷注相关的非即时暗物质候选者。利用基于图神经网络的喷注子结构标记器识别大半径喷注，估计背景，探测信号，未发现显著过量，设定了信号强度上限。
AI 中文摘要
本文介绍了在包含四分支大半径喷注的特征中，对与初态辐射喷注相关产生的一对非即时暗物质（DM）候选者的搜索。信号模型包含一个重矢量或轴矢量媒介子，它产生长寿命暗区粒子，衰变成一个稳定的DM粒子和一个轻玻色子，轻玻色子再衰变成夸克。该分析基于2016 - 2018年用CMS探测器在LHC进行的质子-质子碰撞数据，对应积分亮度为138 fb⁻¹。信号候选者具有大半径喷注，通过基于图神经网络的喷注子结构标记器识别。大半径喷注旨在重建轻DM媒介子衰变成四个夸克的过程，这与两个稳定的DM粒子相关产生。标准模型背景贡献通过专用控制区从数据中估计。对缺失横向动量谱探测潜在信号，未观察到超过标准模型预期的显著过量。在95%置信水平上设定了信号强度作为媒介子质量或相关耦合函数的上限。这是首次在以大半径喷注和大缺失横向动量为特征的洛伦兹增强拓扑中搜索一对非即时DM候选者。
英文摘要
A search for a pair of nonprompt dark matter (DM) candidates produced in association with an initial-state radiation jet, in a signature containing a four-prong large-radius jet, is presented. The signal model contains a heavy vector or axial-vector mediator, which produces long-lived dark-sector particles that decay to a stable DM particle and a light boson, which decays to quarks. The analysis is based on data collected in the years 2016$-$2018 with the CMS detector at the LHC in proton-proton collisions at $\sqrt{s}$ = 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. Signal candidates feature large-radius jets, which are identified using a jet substructure tagger based on a graph neural network. The large-radius jet aims to reconstruct the decay of light DM mediators into four quarks, which are produced in association with two stable DM particles. The standard model background contributions are estimated from data using dedicated control regions. The missing transverse momentum spectrum is probed for a potential signal over the expected background. No significant excess over the standard model expectation is observed. Upper limits at 95% confidence level are set on the signal strength as functions of either the mediator mass or the relevant coupling. This is the first search for a pair of nonprompt DM candidates in the Lorentz-boosted topology, characterized by a large-radius jet and large missing transverse momentum.
CommentsThis version has an updated author list. Submitted to the Journal of High Energy Physics. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/EXO-24-001 (CMS Public Pages)
