Antihydrogen and Fundamental Physics
Antihydrogen and Fundamental Physics
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DOI：
10.1007/978-3-030-51713-7
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
M. Charlton;S. Eriksson;G. Shore
中科院分区：
文献类型：
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作者：
M. Charlton;S. Eriksson;G. Shore
最近由ALPHA合作测量的1 S-2S反氢谱线的精度为1012年的几个部分[1，2]，标志着精确反原子物理学新时代的开始。反氢和其他反物质物种的未来实验将使相对论量子场论和广义相对论的许多基本原理，如CPT不变性，洛伦兹对称性和等效原理，得到非常高的精度测试。因此，现在是时候批判性地审视这些实验中的每一个都可以说是在测试什么，以及任何违背标准期望的行为对基础物理学意味着什么。从这个角度来看，纯反物质系统的实验，无论是基本粒子还是束缚态（如反氢），都特别有趣，因为它们直接受到标准模型基本原理的约束。例如，新的Z玻色子、右手中微子、超对称暗物质候选者等的发现将引起极大的兴趣，但很容易被吸收到标准模型的扩展中。相反，反氢电荷中性的异常结果，或者氢和反氢的1 S-2S跃迁的差异，将直接影响局域相对论QFT的基础。在这些理论中，洛伦兹不变性和因果关系要求反粒子的存在与相应粒子的质量和自旋以及相反的电荷。此外，根据著名定理[3-6]，对于局部QFT，洛伦兹不变性意味着CPT下的不变性。因此，反物质实验直接检验了这些原理。当我们考虑引力时，情况就不那么清楚了，在引力中，这样的实验常常被当作“等效原理”的检验。困难的是，有几个版本的等效原理在文献中弱，强，爱因斯坦的定义并不总是唯一的或明确的。事实上，正如Damour [7]所强调的那样，在更严格的意义上，洛伦兹对称性和因果性是QFT的原则，这不应该被真正视为GR的“原则”。一个更令人满意的方法是认识到我们有一个良好的-
The recent measurement by the ALPHA collaboration of the 1S–2S spectral line in antihydrogen with a precision of a couple of parts in 1012 [1, 2] marks the beginning of a new era of precision anti-atomic physics. Future experiments on antihydrogen and other antimatter species will enable exceptionally high-precision tests of many of the fundamental tenets of relativistic quantum field theory and general relativity, such as CPT invariance, Lorentz symmetry and the Equivalence Principle. It is therefore timely to examine critically what each of these experiments may be said to test and what any violation from standard expectations would mean for fundamental physics. Experiments on pure antimatter systems, whether elementary particles or bound states such as antihydrogen, are especially interesting from this point of view since they are constrained so directly by the fundamental principles underlying the standard model. For example, the discovery of a new Z boson, right-handed neutrinos, a supersymmetric dark matter candidate etc. would be of immense interest but could readily be assimilated into an extension of the standard model. In contrast, an anomalous result on the charge neutrality of antihydrogen, or a difference in the 1S–2S transitions of hydrogen and antihydrogen, would impact directly on the foundations of local relativistic QFT. In these theories, the existence of antiparticles with precisely the mass and spin, and opposite charge, of the corresponding particles is required by Lorentz invariance and causality. Moreover, for a local QFT, Lorentz invariance implies invariance under CPT, according to the celebrated theorem [3–6]. Antimatter experiments therefore directly test these principles. The situation is not so clear when we consider gravity, where such experiments are often presented as tests of “the equivalence principle”. The difficulty is that there are several versions of the equivalence principle in the literature—weak, strong, Einstein—with definitions which are not always either unique or well-defined. Indeed, as emphasised by Damour [7], it should not really be considered as a ‘principle’of GR in the more rigorous sense that Lorentz symmetry and causality are principles of QFT. A more satisfactory approach is to recognise that we have a well-