标题： 中性微子暗物质在升级后的LHC中的湮灭覆盖情况 显示英文标题

标题： On the coverage of neutralino dark matter in coannihilations at the upgraded LHC

摘要： 在超对称模型中，中性微子暗物质与较轻的超对称粒子的共湮灭提供了一种可行的方法来适应观测到的宇宙暗物质残留密度。 这种机制预测了中性微子暗物质及其共湮灭伙伴的压缩谱，导致软最终态，并使对超粒子的搜索在对撞机上具有挑战性。 另一方面，冻结产生的中性微子暗物质的丰度通常随着暗物质质量的增加而增加。 这意味着中性微子暗物质的质量有一个上限。 鉴于这些观察结果，我们探讨了在共湮灭情况下HE-LHC对中性微子暗物质的覆盖范围。 通过分析多 jets 伴随缺失横向能量（$E^{miss}_T$）的事件、单 jets、软轻子对加 $E^{miss}_T$，以及单 jets 加一个强子 tau 的事件，我们发现，在 gluino、stop 和 wino 共湮灭情况下，中性微子暗物质的质量可以分别在 $2\sigma$水平上被排除到 2.6、1.7 和 0.8 TeV。 然而，由于直接 stau 对产生截面较小以及从 stau 衰变中软 tau 的标记效率较低，HE-LHC 对 stau 共湮灭中的中性微子暗物质仍没有灵敏度。 显示英文摘要

摘要： In the supersymmetric models, the coannihilation of the neutralino DM with a lighter supersymmetric particle provides a feasible way to accommodate the observed cosmological DM relic density. Such a mechanism predicts a compressed spectrum of the neutralino DM and its coannihilating partner, which results in the soft final states and makes the searches for sparticles challenging at colliders. On the other hand, the abundance of the freeze-out neutralino DM usually increases as the DM mass becomes heavier. This implies an upper bound on the mass of the neutralino DM. Given these observations, we explore the HE-LHC coverage of the neutralino DM for the coannihilations. By analyzing the events of the multijet with the missing transverse energy ($E^{miss}_T$), the monojet, the soft lepton pair plus $E^{miss}_T$, and the monojet plus a hadronic tau, we find that the neutralino DM mass can be excluded up to 2.6, 1.7 and 0.8 TeV in the gluino, stop and wino coannihilations at the $2\sigma$ level, respectively. However, there is still no sensitivity of the neutralino DM in stau coannihilation at the HE-LHC, due to the small cross section of the direct stau pair production and the low tagging efficiency of soft tau from the stau decay.