Time-reversal violating Schiff moment of 225Ra
Time-reversal violating Schiff moment of 225Ra
复制标题
225Ra 的时间反演破坏希夫矩
DOI：
10.1103/physrevc.68.025501
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
P. Olbratowski
中科院分区：
文献类型：
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作者：
Jonathan Engel;Michael Bender;J. Dobaczewski;J. H. D. Jesus;P. Olbratowski
K和B介子的实验表明，时间反演不变性~T！通过影响弱相互作用@1#的Cabibbo-Kobayashi-Maskawa矩阵中的相位违反。怀疑超标准模型物理，例如，超对称性，也违反了T激发了一种不同的实验：测量电偶极矩~ EDM！中子和原子。因为任何这样的偶极矩必须与T奇自旋算符的期望值成比例，所以它只能在T和宇称P）被违反@2，3 π时存在。到目前为止，这些实验还没有测量到偶极矩，但它们继续改进，甚至零结果也是有用的，因为它们严重限制了新的物理学。因此，无论未来的实验情况如何，重要的是从理论上确定在给定水平上存在或不存在EDM意味着在基本粒子尺度上的T破坏相互作用。这里我们的重点是原子，对于某些T破坏源，目前提供的限制与中子@4#一样好或更好。一个原子可以发展EDM的一种方式是通过其原子核中的T和P破坏。我们假设，给定对称性破缺的一个基本来源，我们可以用有效场论和QCD来计算由此产生的T-破坏核子-π介子相互作用的强度。然后需要将这种相互作用的强度与所产生的核“希夫矩”联系起来，因为核EDM在5 #处被屏蔽，所以它是负责在绕核运行的电子中诱导EDM的量。Schiff矩被经典地定义为一种径向加权的偶极矩：
Experiments with K and B mesons indicate that timereversal invariance ~T! is violated through phases in the Cabibbo-Kobayashi-Maskawa matrix that affect weak interactions @1#. The suspicion that extra-standard-model physics, e.g., supersymmetry, also violates T has motivated a different kind of experiment: measuring the electric dipole moments ~EDMs! of the neutron and atoms. Because any such dipole moment must be proportional to the expectation value of the T-odd spin operator, it can only exist when T ~and parity, P) is violated @2,3#. So far the experiments have measured no dipole moments, but they continue to improve and even null results are useful, since they seriously constrain new physics. Whatever the experimental situation in the future, therefore, it is important to determine theoretically what the presence or absence of EDMs at a given level implies about T-violating interactions at elementary-particle scales. Our focus here is on atoms, which for some sources of T violation currently provide limits as good or better than the neutron @4#. One way an atom can develop an EDM is through T and P violation in its nucleus. Let us assume that given a fundamental source of the broken symmetry, one can use effectivefield theory and QCD to calculate the strength of the resulting T-violating nucleon-pion interaction. One then needs to connect the strength of that interaction to the resulting nuclear ‘‘Schiff moment,’’ which, because the nuclear EDM is screened @5#, is the quantity responsible for inducing an EDM in electrons orbiting the nucleus. The Schiff moment is defined classically as a kind of radially weighted dipole moment: S5 1