论文标题
在$ \ sqrt {s} = 13 $ tev中搜索衰减至准直的lept子或轻质黑龙的光长的中性颗粒
Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
论文作者
论文摘要
搜索在$ O $（MEV-GEV）范围内的光寿命长的中性颗粒。该分析以通过Gluon-Gluon融合或与$ W $ Boson相关的Higgs玻色子的衰减中的长寿命深色光子的产生。包含在量热计或MUON光谱仪中重建的流离失所的准标准模型费米子在139 fb $^{ - 1} $中选择了$ \ sqrt {s} = 13 $ tev $ pp $ pp $ collision数据，该数据由LHC在LHC上收集的碰撞数据。从数据中提取了来自标准模型过程和工具效应的贡献的背景估计。观察到的事件产量与预期背景一致。在生产横截面时间分支分数中报告了排除限制，这是深色光子的平均衰减长度$cτ$的函数，或者是暗光子质量和动力学混合参数的函数，该参数量化了标准模型和电势隐藏（黑暗）扇形之间的耦合。 Higgs玻色子分支的分数以上1％以上的位置为95％Cl，用于Higgs玻色子腐烂成两个深色光子，用于深色光子，平均衰减长度在10 mm至250 mm和250 mm和深色光子之间，质量为0.4 GEV和2 GEV。
A search for light long-lived neutral particles with masses in the $O$(MeV-GeV) range is presented. The analysis targets the production of long-lived dark photons in the decay of a Higgs boson produced via gluon-gluon fusion or in association with a $W$ boson. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are selected in 139 fb$^{-1}$ of $\sqrt{s} = 13$ TeV $pp$ collision data collected by the ATLAS detector at the LHC. Background estimates for contributions from Standard Model processes and instrumental effects are extracted from data. The observed event yields are consistent with the expected background. Exclusion limits are reported on the production cross-section times branching fraction as a function of the mean proper decay length $cτ$ of the dark photon, or as a function of the dark-photon mass and kinetic mixing parameter that quantifies the coupling between the Standard Model and potential hidden (dark) sectors. A Higgs boson branching fraction above 1% is excluded at 95% CL for a Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 10 mm and 250 mm and dark photons with masses between 0.4 GeV and 2 GeV.
