The Neutron and Its Role in Cosmology and Particle Physics
The Neutron and Its Role in Cosmology and Particle Physics
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DOI：
10.1103/revmodphys.83.1111
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发表时间：
2011-05
影响因子：
44.1
通讯作者：
D. Dubbers;M. G. Schmidt
中科院分区：
文献类型：
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作者：
D. Dubbers;M. G. Schmidt
冷中子和超冷中子的实验已经达到了一定的精确度，以至于远远超出目前粒子物理标准模型范围的问题都可以通过实验研究来解决。由于粒子物理学和宇宙学之间的密切联系，这些研究也允许深入研究我们宇宙的最初实例。本文首先从理论和实验两个方面讨论了重子生成问题，这是宇宙中物质明显优于反物质的机制。重子生成是如何发生的问题有待实验检验，事实证明，这个问题可以通过对中子电偶极矩的非常严格的限制来解决，这个量对粒子物理学也有深刻的影响。然后讨论了最近在地球引力场中子量子化和这种引力能态之间共振跃迁的壮观观测。这些测量结果，加上对中子散射数据的新评估，在皮米尺度上对牛顿引力定律的偏差设定了新的限制。这种偏差在现代理论中被预测为额外的维度，这些理论提出了普朗克尺度与更标准模型尺度的统一。这些实验开始关闭亚毫米范围内新的自旋相关力的剩余“轴子窗口”。另一个主要议题是物理学和天体物理学各个领域中的弱相互作用参数，这些参数都必须从测量的中子衰变数据中导出。到目前为止，已经测量了大约10种不同的中子衰变观测值，远远超过了电弱标准模型的需要。这允许对标准模型之外的新物理进行各种精确的测试，与高能下的类似测试竞争或超越。评论结束时，在“前三分钟”和后来的恒星核合成的元素合成所需的中子和核数据的讨论。«少
Experiments with cold and ultracold neutrons have reached a level of precision such that problems far beyond the scale of the present standard model of particle physics become accessible to experimental investigation. Because of the close links between particle physics and cosmology, these studies also permit a deep look into the very first instances of our Universe. First addressed in this article, in both theory and experiment, is the problem of baryogenesis, the mechanism behind the evident dominance of matter over antimatter in the Universe. The question of how baryogenesis could have happened is open to experimental tests, and it turns out that this problem can be curbed by the very stringent limits on an electric dipole moment of the neutron, a quantity that also has deep implications for particle physics. Then the recent spectacular observation of neutron quantization in the Earth's gravitational field and of resonance transitions between such gravitational energy states is discussed. These measurements, together with new evaluations of neutron scattering data, set new constraints on deviations from Newton's gravitational law at the picometer scale. Such deviations are predicted in modern theories with extra dimensions that propose unification of the Planck scale with the scale of themore » standard model. These experiments start closing the remaining ''axion window'' on new spin-dependent forces in the submillimeter range. Another main topic is the weak-interaction parameters in various fields of physics and astrophysics that must all be derived from measured neutron-decay data. Up until now, about 10 different neutron-decay observables have been measured, much more than needed in the electroweak standard model. This allows various precise tests for new physics beyond the standard model, competing with or surpassing similar tests at high energy. The review ends with a discussion of neutron and nuclear data required in the synthesis of the elements during the ''first three minutes'' and later on in stellar nucleosynthesis.« less