Cp Violation Without Strangeness
Cp Violation Without Strangeness
复制标题
违反cp无怪异
DOI：
10.1007/978-3-642-60838-4
复制
发表时间：
1997
影响因子：
2.9
通讯作者：
S. Lamoreaux
中科院分区：
文献类型：
--
作者：
I. Khriplovich;S. Lamoreaux
自1950年以来，电偶极矩（EDM）就引起了物理学家的兴趣，当时首次提出没有实验证据表明核力在宇称（P）变换下是对称的。这个问题被认为是推测性的，因为EDM的存在，除了P破坏之外，还需要时间反演（T）对称性的破坏。1964年，人们发现在CP变换下，结合电荷共轭（C）和宇称的不变性在K介子衰变中被破坏。这为EDM搜索提供了新的动力。由于CPT的组合操作预计会留下一个系统不变，CP不变性的崩溃应该伴随着时间反演对称性的破坏。因此，有理由期待EDM应该在某种程度上存在。最初的中子EDM实验后来补充了原子和分子中T不变性的检查。现在许多团体都在进行这些调查。多年来，中子EDM的上限已经提高了七个数量级，原子实验中获得的电子EDM的上限更加严格。
Electric dipole moments (EDMs) have interested physicists since 1950, when it was first suggested that there was no experimental evidence that nuclear forces are symmetric under parity (P) transformation. This question was regarded as speculative because the existence of an EDM, in addition to P violation, requires a violation of time-reversal (T) symmetry. In 1964 it was discovered that the invariance under CP transformation, which combines charge conjugation (C) with parity, is violated in K-meson decays. This provided a new incentive for EDM searches. Since the combined operations of CPT are expected to leave a system invariant, breakdown of CP invariance should be accompanied by a violation of time-reversal symmetry. Thus there is a reason to expect that EDMs should exist at some level. The original neutron EDM experiments were later supplemented with checks of T invariance in atoms and molecules. These investigations are pursued now by many groups. Over the years, the upper limit on the neutron EDM has been improved by seven orders of magnitude, and the upper limit on the electron EDM obtained in atomic experiments is even more strict.