Long-lived particles at the energy frontier: the MATHUSLA physics case
Long-lived particles at the energy frontier: the MATHUSLA physics case
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DOI：
10.1088/1361-6633/ab28d6
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发表时间：
2018-06
影响因子：
18.1
通讯作者：
D. Curtin;M. Drewes;Matthew McCullough;P. Meade;R. Mohapatra;J. Shelton;B. Shuve;E. Accomando-
中科院分区：
文献类型：
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作者：
D. Curtin;M. Drewes;Matthew McCullough;P. Meade;R. Mohapatra;J. Shelton;B. Shuve;E. Accomando-
我们在对标准模型（SM）扩展的全面调查中，研究了LHC中长寿命粒子（LLP）信号的理论动机。llp是一种广泛的理论预测，用于解决未解决的基本谜团，如自然性、暗物质、重子生成和中微子质量，并代表了超越SM （BSM）的物理学的自然和通用可能性。在大多数情况下，LLP寿命可以被视为从m尺度到大爆炸核合成极限m的自由参数。寿命超过100 m的中性LLP特别难以探测，因为大型强子对撞机主探测器的灵敏度受到具有挑战性的背景、触发器和小接受度的限制。MATHUSLA是ATLAS或CMS附近的最小仪器，大体积表面探测器的建议。它将通过在低背景环境中重建位移顶点（DVs）来寻找HL-LHC碰撞中产生的中性llp，在长寿命状态下将主探测器的灵敏度提高几个数量级。我们研究了HL-LHC上类似mathusla的探测器提供的LLP物理机会，假设背景可以像预期的那样被拒绝。我们开发了一种独立于模型的方法来描述MATHUSLA对BSM LLP信号的灵敏度，并将其与ATLAS或CMS上的DV和缺失能量搜索进行比较。然后，我们相当详细地探讨了llp的BSM动机，提出了大量新的敏感性研究。虽然我们的讨论主要是针对MATHUSLA的长寿命机制，但这项调查强调了大型强子对撞机中各种LLP搜索计划的重要性。通过将这些结果综合到对LLP搜索的自上而下和自下而上动机的一般性讨论中，我们的目标是展示构建MATHUSLA探测器的物理案例的特殊强度和广度。
We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of standard model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the m scale up to the Big Bang Nucleosynthesis limit of m. Neutral LLPs with lifetimes above 100 m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging backgrounds, triggers, and small acceptances. MATHUSLA is a proposal for a minimally instrumented, large-volume surface detector near ATLAS or CMS. It would search for neutral LLPs produced in HL-LHC collisions by reconstructing displaced vertices (DVs) in a low-background environment, extending the sensitivity of the main detectors by orders of magnitude in the long-lifetime regime. We study the LLP physics opportunities afforded by a MATHUSLA-like detector at the HL-LHC, assuming backgrounds can be rejected as expected. We develop a model-independent approach to describe the sensitivity of MATHUSLA to BSM LLP signals, and compare it to DV and missing energy searches at ATLAS or CMS. We then explore the BSM motivations for LLPs in considerable detail, presenting a large number of new sensitivity studies. While our discussion is especially oriented towards the long-lifetime regime at MATHUSLA, this survey underlines the importance of a varied LLP search program at the LHC in general. By synthesizing these results into a general discussion of the top–down and bottom-up motivations for LLP searches, it is our aim to demonstrate the exceptional strength and breadth of the physics case for the construction of the MATHUSLA detector.