论文标题
关于在LHC上寻找GEV规模的长寿命颗粒的挑战
On the challenges of searching for GeV-scale long-lived particles at the LHC
论文作者
论文摘要
许多暗物质模型可以预测长寿命颗粒（LLP），可以在LHC处引起惊人的特征。但是，现有对流离失所顶点的搜索是针对重型LLP量身定制的。在这项工作中，我们表明，这种偏见严重影响了他们对LLP的敏感性，其质量在GEV量表上。为了说明这一点，我们考虑了两个黑暗扇区模型，其淡淡的LLP会衰减强调：一个具有长期寿命的异国情调介子的强烈相互交互的黑暗扇形，以及一个带有长寿的黑暗higgs玻色子的希格斯黑暗扇形。我们研究了现有的ATLAS在这两个模型中搜索流离失所的顶点和缺少能量的敏感性，发现当前的轨道和顶点削减会导致光LLP的效率非常低。为了缩小当前搜索程序中的差距，我们建议对顶点重建和分析削减的两个可能的修改。我们计算了这些修饰的预测排除限制，并表明它们大大提高了对质量低或短衰减长度的LLP的敏感性。
Many models of dark matter predict long-lived particles (LLPs) that can give rise to striking signatures at the LHC. Existing searches for displaced vertices are however tailored towards heavy LLPs. In this work we show that this bias severely affects their sensitivity to LLPs with masses at the GeV scale. To illustrate this point we consider two dark sector models with light LLPs that decay hadronically: a strongly-interacting dark sector with long-lived exotic mesons, and a Higgsed dark sector with a long-lived dark Higgs boson. We study the sensitivity of an existing ATLAS search for displaced vertices and missing energy in these two models and find that current track and vertex cuts result in very low efficiency for light LLPs. To close this gap in the current search programme we suggest two possible modifications of the vertex reconstruction and the analysis cuts. We calculate projected exclusion limits for these modifications and show that they greatly enhance the sensitivity to LLPs with low mass or short decay lengths.
