发表机构
University of California, Berkeley; University of California, San Diego; Harvard University（加州大学伯克利分校; 加州大学圣迭戈分校; 哈佛大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对LZ实验248 keV事件，提出RS翘曲额外维模型中自然产生的非弹性暗物质候选粒子，通过KK规范玻色子介导，解释信号并规避现有约束。
AI 中文摘要
LUX-ZEPLIN (LZ) 实验最近观测到在 $248\\,\mathrm{keV}$ 处的一个单核反冲事件，这暗示着暗物质 (DM) 与氙靶之间可能发生了非弹性散射。广泛考虑的热希格斯子暗物质，其质量 $m_{\chi}\sim$ TeV 且质量劈裂 $\delta \sim 350$ keV，基本上已被排除，因为这种暗物质会被太阳有效俘获，其湮灭产生的中微子通量将超过 IceCube 的极限，并且预期的反冲能量高于 LZ 的名义搜索窗口，而该窗口内未观测到任何事件。然而，我们认为，尽管这些矛盾适用于具有受限截面的希格斯子，但它们不一定适用于更广泛的非弹性候选粒子，这些候选粒子可能由层级问题的替代解决方案所暗示。我们表明，一种新的有质量规范玻色子 $Z'$，其候选暗物质扇区具有约为狄拉克质量 $\sim 10^{-7}$ 量级的马约拉纳质量劈裂，可以规避当前的约束。我们提出了一种非弹性暗物质 (iDM) 候选粒子，它可以在 Randall-Sundrum 翘曲额外维模型中自然产生。该暗物质候选粒子涉及一个被限制在 TeV 膜上的矢量费米子以及一个体场。膜上的拉格朗日量包含狄拉克质量项，这些项也自然地被指数抑制。体场的左手分量具有一个起源于紫外 (UV) 膜上的马约拉纳质量，而它与标准模型核子的相互作用由一个有质量的暗卡鲁扎-克莱因 (KK) 规范玻色子介导，该玻色子的质量也自动处于正确的范围内。我们提出了一个具体的热暗物质模型，其 $m_{\chi}\sim$ TeV，位于具有翘曲因子 $\pi kR\simeq 31.7$ 的 RS 几何中，$Z'$ 是一个 KK 模式，具有自然的 TeV 量级质量，其中中微子与夸克耦合之比也是自然的，从而产生 $\delta \sim 300$ keV 的质量劈裂，并展示了它如何能够解释 LZ 信号，同时与现有约束保持一致。
英文摘要
The recent result by the LUX-ZEPLIN (LZ) experiment of a single nuclear-recoil event at $248\,\mathrm{keV}$ suggests an interpretation in terms of inelastic scattering between dark matter (DM) and the xenon target. The widely considered thermal Higgsino DM with $m_χ\sim$~TeV and mass splitting $δ\sim 350$~keV is essentially excluded as it would be captured efficiently by the Sun, with a resulting neutrino flux from its annihilation in excess of the IceCube limit, and expected recoils above the LZ nominal search window, where none were seen. However we argue that although these tensions apply to a Higgsino with constrained cross section, they need not apply to the broader set of inelastic candidates that alternative solutions to the hierarchy problem might suggest. We show that a new massive gauge boson, $Z'$ with a candidate DM sector and Majorana mass splitting of order $\sim 10^{-7}$ of the Dirac mass, evades current constraints. We propose an inelastic dark matter (iDM) candidate that can arise naturally in a Randall-Sundrum warped extra-dimensional model. The DM candidate involves a vector-like fermion confined to the TeV brane and a bulk field. The brane Lagrangian contains Dirac mass terms that are also naturally exponentially suppressed. The left-handed component of the bulk field has a Majorana mass with origin on the UV brane, while the interaction with Standard Model nucleons is mediated by a massive dark Kaluza-Klein (KK) gauge boson whose mass is also automatically in the right range. We propose a concrete model of thermal DM with $m_χ\sim$~TeV in an RS geometry with warp factor $πkR\simeq 31.7$ and the $Z'$ a KK mode with natural TeV-ish scale mass in which the ratio of neutrino to quark coupling is also natural, giving a mass splitting of $δ\sim 300$~keV, and show how it could explain the LZ signal while being consistent with existing constraints.
Comments5+1 pages, 2 figures
