发表机构
University of California, Davis; Università degli Studi di Bergamo; Imperial College London（加州大学戴维斯分校; 贝加莫大学; 帝国理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出安装在LHC的CMS点5号PX56廊道的专用探测器GRENDEL，利用岩石混凝土被动屏蔽与主动本底排除，以挤出闪烁体棒探测0.2-15GeV的中性长寿命粒子，无需土木工程即可实现有竞争力的灵敏度。
AI 中文摘要
长寿命粒子是标准模型扩展理论的普遍预测，这类理论旨在解决等级问题、中微子质量起源、宇宙重子不对称性以及暗物质本质等问题。尽管理论动机广泛，但GeV质量范围的中性长寿命粒子仍难以在LHC的主探测器中被探测到——触发限制和棘手的本底会削弱探测器在很大寿命范围内的灵敏度。我们提出GRENDEL（GalleRy ExperimeNt for Decays of Exotic LLPs，奇异长寿命粒子衰变画廊实验），这是一台将安装在CMS实验5号点PX56排水廊道中的专用探测器。GRENDEL将利用探测器与LHC相互作用点之间的大量岩石和混凝土作为被动屏蔽，同时还会采用主动本底排除技术。该探测器位于相互作用点上方约22米处，大致沿束流横向方向延伸，总长约110米，覆盖中心快度区|η|<0.6。GRENDEL将采用挤出型闪烁体棒，在仅需最少基础设施且无需土木工程的前提下，实现与其他拟建探测器相当的竞争力灵敏度。我们介绍了该实验的物理依据、探测器概念，以及利用3 ab⁻¹的高亮度LHC（HL-LHC）数据，对质量范围在0.2-15 GeV的重中性轻子、暗标量和类轴子粒子的预计灵敏度。这些基准模型覆盖中微子门、标量门和轴子门，粒子产生途径包括希格斯粒子的奇异衰变、B介子和D介子衰变以及W/Z玻色子衰变。
英文摘要
Long-lived particles are a generic prediction of Standard Model extensions that address the hierarchy problem, the origin of neutrino masses, the baryon asymmetry of the Universe, and the nature of dark matter. Despite the breadth of theoretical motivation, neutral long-lived particles in the GeV-scale mass range remain difficult to probe at the LHC main detectors, where trigger limitations and challenging backgrounds curtail sensitivity over a wide range of lifetimes. We propose GRENDEL (GalleRy ExperimeNt for Decays of Exotic LLPs), a dedicated detector to be installed in the PX56 drainage gallery at CMS Point 5. GRENDEL will exploit the substantial rock and concrete between the detector and LHC interaction point as passive shielding in addition to employing active background rejection. Located approximately 22 m above the interaction point and running largely transverse to the beam, GRENDEL will span around 110 m and cover the central region $|η| < 0.6$. GRENDEL will make use of extruded scintillator bars to achieve competitive sensitivity with other proposed detectors while requiring minimal infrastructure, and without the need for civil engineering. We present the physics case, detector concept, and projected sensitivities to heavy neutral leptons, dark scalars, and axion-like particles covering the $0.2-15$ GeV mass range with 3 $\mathrm{ab}^{-1}$ of HL-LHC data. The benchmarks span the neutrino, scalar, and axion portals, with production through exotic Higgs decays, $B$- and $D$-meson decays, and $W/Z$ decays.
Comments18 pages, 6 figures
