Inelastic frontier: Discovering dark matter at high recoil energy
Inelastic frontier: Discovering dark matter at high recoil energy
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DOI：
10.1103/physrevd.94.115026
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发表时间：
2016-12-27
影响因子：
5
通讯作者：
Martin, Adam
中科院分区：
文献类型：
--
作者：
Bramante, Joseph;Fox, Patrick J.;Martin, Adam
在直接探测实验中，粒子暗物质主要以非弹性方式在原子核外散射，存在动机良好的粒子暗物质模型。这种非弹性转变导致暗物质在地面实验中发生上散射，进入比暗物质本身重达550keV的激发状态。这种大小的非弹性转变受到运动学和原子核形状因子的高度抑制。在这篇文章中，我们扩展了前人对非弹性暗物质的研究，以确定目前散射截面的界限和提高灵敏度的前景。三个场景提供了说明性的例子：几乎纯的Higgsino超对称暗物质，磁性非弹性暗物质，以及具有暗光子交换的非弹性模型。我们确定了弹性散射率(通过涉及重态的环图)，并验证了放热跃迁可以忽略不计(在我们考虑的参数空间中)。目前，截面上最强的边界来自LUX-PandaX处的氙气(当质量分裂增量小于或接近160keV时)，碘在皮科处(当160小于或类似于增量小于或等于300keV时)，以及钨在CRESST处(当增量大于或类似于300keV时)。有趣的是，一旦增量大于或类似于200keV，暗物质-核子的弱尺度(和更大)散射截面是允许的。这些不同实验的相对竞争力取决于每个实验所使用的反冲能量的上限，以及对探测器中最重元素的质量的强烈敏感性。讨论了几个方面的意义，包括相当大的反冲能量依赖的年度调制和对未来实验的改进。我们表明，氙气实验可以改进皮科实验的结果，如果他们要分析他们现有的数据在更大的反冲能量范围内，即20-500keV有趣的是，CRESST已经报告了几个在45-100keV的反冲能量范围内的事件，如果解释为暗物质散射，则与类似于200keV的增量相容，并且具有大约弱的标度截面。来自Pico和CRESST的未来数据可以检验这一推测，而氙气实验可以通过分析他们更高的能量反冲数据来验证或驳斥这一点。
There exist well-motivated models of particle dark matter which predominantly scatter inelastically off nuclei in direct detection experiments. This inelastic transition causes the dark matter to upscatter in terrestrial experiments into an excited state up to 550 keV heavier than the dark matter itself. An inelastic transition of this size is highly suppressed by both kinematics and nuclear form factors. In this paper, we extend previous studies of inelastic dark matter to determine the present bounds on the scattering cross section and the prospects for improvements in sensitivity. Three scenarios provide illustrative examples: nearly pure Higgsino supersymmetric dark matter, magnetic inelastic dark matter, and inelastic models with dark photon exchange. We determine the elastic scattering rate (through loop diagrams involving the heavy state) as well as verify that exothermic transitions are negligible (in the parameter space we consider). Presently, the strongest bounds on the cross section are from xenon at LUX-PandaX (when the mass splitting delta less than or similar to 160 keV), iodine at PICO (when 160 less than or similar to delta less than or similar to 300 keV), and tungsten at CRESST (when delta greater than or similar to 300 keV). Amusingly, once delta greater than or similar to 200 keV, weak scale (and larger) dark matter-nucleon scattering cross sections are allowed. The relative competitiveness of these diverse experiments is governed by the upper bound on the recoil energies employed by each experiment, as well as strong sensitivity to the mass of the heaviest element in the detector. Several implications, including sizable recoil energy-dependent annual modulation and improvements for future experiments, are discussed. We show that the xenon experiments can improve on the PICO results, if they were to analyze their existing data over a larger range of recoil energies, i.e., 20-500 keV Intriguingly, CRESST has reported several events in the recoil energy range 45-100 keV that, if interpreted as dark matter scattering, is compatible with delta similar to 200 keV and an approximately weak scale cross section. Future data from PICO and CRESST can test this speculation, while xenon experiments could verify or refute this upon analyzing their higher energy recoil data.