标题： 标准模型的多单态扩展中的暗物质 显示英文标题

标题： Dark Matter in Multi-Singlet Extensions of the Standard Model

摘要： 我们研究了标准模型（SM）最简单的扩展，这些扩展产生了暗物质（DM）候选者，构建方式是在模型中加入实数单态以及新的${Z}_2$对称性，使得模型在这种对称性下保持不变。在这种类型的模型中，除了源自连接SM希格斯与DM候选者的门户耦合的新相互作用外，SM粒子之间的相互作用未被改变。 在只有一个单态的扩展中，根据遗迹密度和直接探测（DD）约束的组合，低于约4 TeV的DM质量已经被排除，但共振情况下为Higgs质量的一半除外，这使得它们在LHC中无法被探测到。增加具有独立${Z}_2$对称性的更多实数单态会为其中一个DM候选者打开一个新的质量窗口，并降低另一个的质量下限。如果再增加具有独立${Z}_2$对称性的更多单态，这种图像不会发生显著变化。 相反，如果我们添加的所有新单态都对同一${Z}_2$对称性奇，则DM候选者（即较轻的暗物质标量）的质量允许区域将覆盖从Higgs质量的一半到TeV尺度的整个范围。原则上，这些较轻的粒子可能在LHC中的单$X$探测中被探测到。尽管目前LHC的DM搜索仍无法触及它们，但在LHC的高亮度（HL-LHC）阶段，有很好的机会在某些最终状态下探测到这些模型。 显示英文摘要

摘要： We study the simplest extensions of the Standard Model (SM) that originate Dark Matter (DM) candidates, built with the addition of real singlets and new ${Z}_2$ symmetries under which the models are invariant. In this type of models the interactions between SM particles are not altered except for the new interactions stemming from the portal couplings that link the SM Higgs with the DM candidates. In the extension with just one singlet, DM masses below about 4 TeV are already excluded by the combination of relic density and direct detection (DD) constraints, except for the resonant case of half the Higgs mass, making them undetectable at the LHC. Adding more real singlets with independent ${Z}_2$ symmetries opens up a new mass window for one of the DM candidates and decreases the lower bound on the other. Adding more singlets with independent ${Z}_2$ symmetries will not change this picture dramatically. If instead we add new singlets all odd under the same ${Z}_2$ symmetry, the allowed mass region for the DM candidate (i.e., the lighter dark sector scalar) will span the entire mass range from half the Higgs mass to the TeV scale. In principle, such light particles could be probed at the LHC in mono-$X$ searches. Although they are still out of reach with the current LHC DM searches, there are good chances to probe the models in some final states at the High-Luminosity (HL-LHC) stage of the LHC.