标题： 在LEP上使用DELPHI探测器搜索LSP胶微子 显示英文标题

标题： Search for an LSP gluino at LEP with the DELPHI detector

摘要： 在一些超对称模型中，胶微子被预测为轻且稳定的。在这种情况下，它将形成R-强子。在这些模型中，最轻的超对称粒子的缺失能量信号不再有效，即使R-宇称被守恒。因此，这种胶微子不受强子对撞机结果的约束，这些结果寻找胶微子衰变为q qbar\tilde{\chi}_1^0的衰变。1994年在91.2 GeV下由DELPHI探测器收集的数据已被分析以搜索(q qbar胶微子胶微子)事件。未观察到与标准模型预测的偏差，并且在这些模型中，在95%置信度水平下排除了2到18 GeV/c^2之间的胶微子质量。然后，在DELPHI在质心系能量189至208 GeV下收集的数据中搜索了在squark衰变中产生的R-强子，对应于总积分亮度609 pb^-1。观测到的事件数与标准模型预测一致。从平面(m_\tilde{q_1},m_gluino)中的排除区域推导出了95%置信度水平下的squark质量限制：对于纯左旋squark，m_\tilde{t_1}> 90 GeV/c^2，和m_\tilde{b_1}> 96 GeV/c^2。m_\tilde{t_1}> 87 GeV/c^2，和m_\tilde{b_1}> 82 GeV/c^2，与混合角无关。 显示英文摘要

摘要： In some supersymmetric models, the gluino is predicted to be light and stable. In that case, it would hadronize to form R-hadrons. In these models, the missing energy signature of the lightest supersymmetric particle is no longer valid, even if R-parity is conserved. Therefore, such a gluino is not constrained by hadron collider results, which looked for the decay gluino -> q qbar \tilde{\chi}_1^0. Data collected by the DELPHI detector in 1994 at 91.2 GeV have been analysed to search for (q qbar gluino gluino) events. No deviation from Standard Model predictions is observed and a gluino mass between 2 and 18 GeV/c^2 is excluded at the 95% confidence level in these models. Then, R-hadrons produced in the squark decays were searched for in the data collected by DELPHI at the centre-of-mass energies of 189 to 208 GeV, corresponding to an overall integrated luminosity of 609 pb^-1. The observed number of events is in agreement with the Standard Model predictions. Limits at 95% confidence level are derived on the squark masses from the excluded regions in the plane (m_\tilde{q_1},m_gluino): m_\tilde{t_1} > 90 GeV/c^2, and m_\tilde{b_1} > 96 GeV/c^2 for purely left squarks. m_\tilde{t_1} > 87 GeV/c^2, and m_\tilde{b_1} > 82 GeV/c^2 independent of the mixing angle.