什么是暗物质?  

What is dark matter?

作　　者：毕效军[1] 范一中[2] 岳骞 周宇峰[4] Xiaojun Bi;Yizhong Fan;Qian Yue;Yufeng Zhou(Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210034,China;Departments of Physics,Tsinghua University,Beijing 100084,China;Institute of Theoretical Physics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]中国科学院高能物理研究所,北京100049 [2]中国科学院紫金山天文台,南京210034 [3]清华大学物理系,北京100084 [4]中国科学院理论物理研究所,北京100190

出　　处：《科学通报》2018年第24期2413-2421,共9页Chinese Science Bulletin

摘　　要：虽然暗物质的存在已经得到了大量的天文观测的支持,但暗物质的属性是什么仍然是个未解之谜.近期暗物质探测的实验和理论研究均取得了长足的进展.本文从暗物质问题的提出讲起,介绍了暗物质的基本特点和可能的粒子物理候选者,之后详细介绍了暗物质研究的最新进展.(1)暗物质研究的早期历史.从星系旋转曲线、引力透镜、微波背景辐射等方面介绍了暗物质的观测证据,特别是暗物质丰度起源的标准热退耦理论机制和典型的暗物质粒子候选者,如弱相互作用有质量粒子等.(2)暗物质粒子的实验探测的基本原理和手段,如地下直接探测和空间间接探测等.重点综述了近期实验研究的进展.在地下直接探测方面综述了10 Ge V以下轻质量暗物质的探测实验:Super CDMS(super cryogenic dark matter search),CDEX(China dark matter experiment)等,以及大质量暗物质探测中的液氩探测器Dark Side等.(3)暗物质未来的碰撞方向性探测实验,如DRIFT(directional recoil identification from tracks),MIMAC(MIcro-tpc MAtrix of Chambers)等.在空间间接探测方面介绍暗物质湮灭到宇宙线粒子中涉及到的宇宙线粒子产生和传播的基本理论.(4)已有的实验,如Fermi-LAT(Fermi large area telescope)和AMS(Alpha magnetic spectrometer)-02在高能宇宙线电子和核子方面已经取得的成果,特别是近期DAMPE(dark matter particle explorer)卫星实验的首个结果中看到的正负电子总流强中的新现象和疑似反常现象以及AMS-02的反质子结果对暗物质搜寻的影响.展望了未来在反核子,如反氘和反氦方面可能取得的结果及其对暗物质研究的重要性.This study aims to review the early history of dark matter study, such as observational evidence from galactic rotational curves, gravitational lensing, and the cosmic microwave background, among others. The observation of the bullet clus- ters, which strongly supports the existence of dark matter rather than the theory of modified gravity, is discussed. The N body simulations also suggest the existence of cold non-relativistic dark matter and the existence of a universal form of the dark matter density distribution profile. We introduce a standard mechanism of thermal freeze-out for dark matter relic abundance, i.e., an explanation of how the dark matter particles that were kept in thermal equilibrium in the early stages of the universe are later unable to stay in equilibrium due to the expansion of the universe. The typical dark matter candidates are the so-called WIMPs （weakly interacting massive particles）. Popular WIMP candidates include the lightest supersyrnmetric particles such as neutralinos. Other WIMP candidates such as the lightest T odd particles in the little Higgs models and the lightest KK （Kluza-Klein） modes in the universal extra dimension models are also discussed. Non-WIMP dark matter candidates such as axions are briefly discussed. The basic ideas and methods of dark matter de- tection, such as underground direct detection, which involves dark matter scattering off target nuclei, and indirect detec- tion in space, which involves dark matter annihilation or decay in galaxies, are reviewed with a focus on recent experi- mental developments. For underground direct detection, we begin with the basic formulas for elastic dark matter nuclei scattering and the general features of nuclear number dependence. Three types of observables are discussed： （1） direct recoil events, （2） solar modulation of the recoil events, and （3） directional effects or the day-night differences of the events. Then, we focus on the experiments studying low-mass dark matter below 10 GeV, such as SuperCD

关 键 词：暗物质 直接探测 间接探测 

分 类 号：P145.9[天文地球—天体物理]