"Table 51" of "Search for dark matter produced in association with bottom or top quarks in $\sqrt{s}$ = 13 TeV pp collisions with the ATLAS detector"

A search for weakly-interacting-massive-particle (WIMP) dark matter produced in association with bottom or top quarks is presented. Final states containing third generation quarks and missing transverse momentum are considered. The analysis uses 36.1 fb-1 of proton-proton collisions data recorded by the ATLAS experiment at sqrt(s)=13 TeV in 2015 and 2016. No significant deviation from the background prediction is observed. The results are interpreted in the framework of simplified models of spin-0 dark matter mediators. For colour-neutral spin-0 mediators decaying into a pair of dark matter particles, signals with scalar mediator masses below 50 GeV in top quark final states are excluded, assuming a dark matter mass of 1 GeV and unitary coupling. For bottom quark final states 300 times the value of the production cross section for signals with scalar and pseudoscalar mediator masses between 10 and 50 GeV are excluded, assuming a dark matter mass of 1 GeV and unitary coupling. Constraints on colour-charged scalar simplified models are also presented. Assuming a dark matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding to a dark matter relic density consistent with measurements.

本文报道了针对伴随底夸克或顶夸克产生的弱相互作用大质量粒子（weakly-interacting-massive-particle, WIMP）暗物质的搜索分析。分析考量了包含第三代夸克与缺失横向动量的末态样本。本分析使用了ATLAS实验于2015至2016年间采集的、质心系能量√s=13 TeV的36.1 fb⁻¹质子-质子对撞数据。未观测到与本底预期存在显著偏离的信号。

研究结果基于自旋0暗物质传递子的简化模型框架进行诠释。对于衰变至一对暗物质粒子的色中性自旋0传递子，在暗物质质量为1 GeV且耦合为幺正耦合（unitary coupling）的假设下，顶夸克末态中标量传递子质量低于50 GeV的信号被排除。对于底夸克末态，在暗物质质量为1 GeV且耦合为幺正耦合的假设下，标量与赝标量传递子质量介于10 GeV至50 GeV之间的信号，其产生截面（production cross section）的300倍上限被排除。

本文同时给出了带色标量简化模型的约束结果。在暗物质粒子质量为35 GeV的假设下，对于暗物质遗迹密度（dark matter relic density）与实验测量结果相符的耦合情形，质量低于1.1 TeV的传递子粒子被排除。