ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia.
Phys Rev Lett. 2012 Dec 14;109(24):241801. doi: 10.1103/PhysRevLett.109.241801. Epub 2012 Dec 10.
Natural models of supersymmetry with a gravitino lightest supersymmetric particle provide distinctive signatures at the LHC. For a neutralino next-to-lightest supersymmetric particle, sparticles can decay to two high energy photons plus missing energy. We use the ATLAS diphoton search with 4.8 b(-1) of data to place limits in both the top-squark-gluino and neutralino-chargino mass planes for this scenario. If the neutralino is heavier than 50 GeV, the lightest top squark must be heavier than 580 GeV, the gluino must be heavier than 1100 GeV, and charginos must be heavier than approximately 300-470 GeV. This provides the first nontrivial constraints in natural gauge mediation models with a neutralino next-to-lightest supersymmetric particle decaying to photons and implies a fine-tuning of at least a few percent in such models.
具有轻质量超对称粒子的自然超对称模型在 LHC 上提供了独特的特征。对于近轻超对称粒子的中性微子，粒子可以衰变为两个高能光子加缺失能量。我们使用 ATLAS 双光子搜索，在这个场景中，在 top 夸克-胶子和中性微子-带电微子质量平面上分别设置限制。如果中性微子重于 50GeV，那么最轻的 top 夸克必须重于 580GeV，胶子必须重于 1100GeV，带电微子必须重于大约 300-470GeV。这为具有中性微子近轻超对称粒子衰变为光子的自然规范介接模型提供了第一个非平凡的约束，并暗示了这种模型中至少有几个百分点的微调。
