"TChiHH expected - 1 s.d. mass limit curve" of "Search for higgsinos decaying to two Higgs bosons and missing transverse momentum in proton-proton collisions at $\sqrt{s}$ = 13 TeV"

Results are presented from a search for physics beyond the standard model in proton-proton collisions at $\sqrt{s}=13$ TeV in channels with two Higgs bosons, each decaying via the process H$\to b\overline{b}$, and large missing transverse momentum. The search uses a data sample corresponding to an integrated luminosity of 137 fb$^{-1}$ collected by the CMS experiment at the CERN LHC. The search is motivated by models of supersymmetry that predict the production of neutralinos, the neutral partners of the electroweak gauge and Higgs bosons. The observed event yields in the signal regions are found to be consistent with the standard model background expectations. The results are interpreted using simplified models of supersymmetry. For the electroweak production of nearly degenerate higgsinos, each of whose decay chains yields a neutralino ($\widetilde{\chi}^0_1$) that in turn decays to a massless goldstino and a Higgs boson, $\widetilde{\chi}^0_1$ masses in the range 175 to 1025 GeV are excluded at 95\% confidence level. For the strong production of gluino pairs decaying via a slightly lighter $\widetilde{\chi}^0_2$ to H and a light $\widetilde{\chi}^0_1$, gluino masses below 2330 GeV are excluded.

本研究报道了在欧洲核子研究中心大型强子对撞机（CERN LHC）的CMS实验（CMS）采集的、对应积分亮度（integrated luminosity）为137 fb⁻¹的数据样本中，针对质心系能量$sqrt{s}=13$ TeV的质子-质子碰撞过程中，双希格斯玻色子（Higgs boson）末态（每个希格斯玻色子均通过$ ext{H} o boverline{b}$过程衰变）且伴随大横向缺失动量的超出标准模型（Standard Model）物理信号的搜索结果。本搜索的理论动机来自超对称（supersymmetry）模型，这类模型预言了中性微子（neutralinos）的产生——中性微子是电弱规范玻色子与希格斯玻色子的超对称中性伴子。信号区域内观测到的事例产额（event yield）与标准模型本底预期相符。本结果基于超对称简化模型（simplified supersymmetry model）进行诠释：对于近简并希格斯微子（higgsinos）的电弱产生过程，其每条衰变链均产生中性微子$widetilde{chi}^0_1$，该中性微子随后衰变为无质量金微子（goldstino）与希格斯玻色子，在此情况下，质量介于175 GeV至1025 GeV之间的$widetilde{chi}^0_1$在95%置信水平（confidence level）下被排除；对于通过稍轻的$widetilde{chi}^0_2$衰变至希格斯玻色子与轻中性微子$widetilde{chi}^0_1$的胶微子对（gluino pairs）的强产生过程，质量低于2330 GeV的胶微子在95%置信水平下被排除。