Title: Higgs and $Z$ Assisted Stop Searches at Hadron Colliders Show Chinese title

Title: 希格斯和$Z$伴随停止子搜索在强子对撞机上

Abstract: Current searches for the light top squark (stop) mostly focus on the decay channels of $\tilde{t} \rightarrow t \chi_1^0$ or $\tilde{t} \rightarrow b \chi_1^\pm \rightarrow bW \chi_1^0$, leading to $t\bar{t}/bbWW+\met$ final states for stop pair productions at the LHC. However, in supersymmetric scenarios with light neutralinos and charginos other than the neutralino lightest supersymmetric particle (LSP), more than one decay mode of the stop could be dominant. While those new decay modes could significantly weaken the current stop search limits at the LHC, they also offer alternative discovery channels for stop searches. In this paper, we studied the scenario with light Higgsino next-to-LSPs (NLSPs) and Bino LSP. The light stop decays primarily via $\tilde t_1 \to t \chi_2^0/\chi_3^0$, with the neutralinos subsequent decaying to a $Z$ boson or a Higgs boson: $\chi_2^0/\chi^0_3 \to \chi_1^0 h/Z$. Pair production of light stops at the LHC leads to final states of $t \bar t hh\met$, $t \bar t hZ\met$ or $t \bar t ZZ\met$. We consider three signal regions: one charged lepton (1$\ell$), two opposite sign charged leptons (2 OS $\ell$) and at least three charged leptons ($ \ge 3 \ell$). We found that the 1$\ell$ signal region of channel $t \bar t hZ\met$ has the best reach sensitivity for light stop searches. For 14 TeV LHC with 300 ${\rm fb}^{-1}$ integrated luminosity, a stop mass up to 900 GeV can be discovered at 5$\sigma$ significance, or up to 1050 GeV can be excluded at 95\% C.L. Combining all three decay channels for $1 \ell$ signal region extends the reach for about 100$-$150 GeV. We also studied the stop reach at the 100 TeV $pp$ collider with 3 ${\rm ab}^{-1}$ luminosity, with discovery and exclusion reach being 6 TeV and 7 TeV, respectively. Show Chinese abstract

Abstract: 当前对轻顶夸克（stop）的搜索主要集中在$\tilde{t} \rightarrow t \chi_1^0$或$\tilde{t} \rightarrow b \chi_1^\pm \rightarrow bW \chi_1^0$的衰变通道，导致在大型强子对撞机（LHC）上产生$t\bar{t}/bbWW+\met$最终态的stop对产生。 然而，在除了中性微子最轻超对称粒子（LSP）以外的具有轻中性微子和带电微子的超对称场景中，stop的衰变模式可能不止一种是主导的。 虽然这些新的衰变模式可能会显著削弱LHC上当前的stop搜索限制，但也为stop搜索提供了替代的发现通道。 在本文中，我们研究了具有轻希格斯微子次轻超对称粒子（NLSPs）和Bino LSP的情况。 轻顶夸克主要通过$\tilde t_1 \to t \chi_2^0/\chi_3^0$衰变，其中中性微子随后衰变为$Z$玻色子或希格斯玻色子：$\chi_2^0/\chi^0_3 \to \chi_1^0 h/Z$。 轻停止子在大型强子对撞机上的产生导致最终状态为 $t \bar t hh\met$, $t \bar t hZ\met$或 $t \bar t ZZ\met$。 我们考虑三个信号区域：一个带电轻子 (1$\ell$)，两个不同电荷的带电轻子 (2 OS $\ell$) 和至少三个带电轻子 ($ \ge 3 \ell$)。 我们发现通道$t \bar t hZ\met$的 1$\ell$信号区域对于轻量级停止子搜索具有最佳的探测灵敏度。 对于 14 TeV 的 LHC，300 ${\rm fb}^{-1}$的积分亮度，可以在 5$\sigma$显著性下发现高达 900 GeV 的停止子质量，或者在 95% 置信水平下排除高达 1050 GeV 的停止子质量。 将所有三个衰变通道的$1 \ell$信号区域结合起来，探测范围大约扩展了 100$-$150 GeV。 我们还研究了在100 TeV $pp$ 对撞机上，3 ${\rm ab}^{-1}$ 亮度下的停止点可达性，发现和排除的可达性分别为6 TeV和7 TeV。