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Improved measurement of the shape of the electron

机译：改进了电子形状的测量

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The electron is predicted to be slightly aspheric, with a distortion characterized by the electric dipole moment (EDM), d_e. No experiment has ever detected this deviation. The standard model of particle physics predicts that d_e is far too small to detect, being some eleven orders of magnitude smaller than the current experimental sensitivity. However, many extensions to the standard model naturally predict much larger values of d_e that should be detectable. This makes the search for the electron EDM a powerful way to search for new physics and constrain the possible extensions. In particular, the popular idea that new supersymmetric particles may exist at masses of a few hundred GeV/c~2 (where c is the speed of light) is difficult to reconcile with the absence of an electron EDM at the present limit of sensitivity. The size of the EDM is also intimately related to the question of why the Universe has so little antimatter. If the reason is that some undiscovered particle interaction breaks the symmetry between matter and antimatter, this should result in a measurable EDM in most models of particle physics2. Here we use cold polar molecules to measure the electron EDM at the highest level of precision reported so far, providing a constraint on any possible new interactions. We obtain d_e= (-2.4 ± 5.7_(stat)± 1.5_(syst)) × 10~(-28)ecm, where eis the charge on the electron, which sets a new upper limit of |d_e| < 10.5 × 10~(-28)ecm with 90 per cent confidence. This result, consistent with zero, indicates that the electron is spherical at this improved level of precision. Our measurement of atto-electronvolt energy shifts in a molecule probes new physics at the tera-electronvolt energy scale.
机译：预计电子将是非球面的，其畸变的特征在于电偶极矩（EDM）d_e。没有实验能检测到这种偏差。粒子物理学的标准模型预测d_e太小而无法检测，比当前的实验灵敏度小11个数量级。但是，对标准模型的许多扩展自然会预测应该检测到的更大的d_e值。这使搜索电子EDM成为搜索新物理学并限制可能的扩展的有力方法。特别是，在目前的灵敏度极限下，缺乏电子EDM很难协调新的超对称粒子可能以几百个GeV / c〜2（其中c是光速）的质量存在的普遍想法。 EDM的大小也与为何宇宙反物质如此之少的问题密切相关。如果原因是某些未发现的粒子相互作用破坏了物质与反物质之间的对称性，那么在大多数粒子物理学模型中，这应该导致可测量的EDM2。在这里，我们使用冷极性分子以迄今报道的最高精确度来测量电子EDM，从而限制了任何可能的新相互作用。我们得到d_e =（-2.4±5.7_（stat）±1.5_（syst））×10〜（-28）ecm，其中e是电子上的电荷，它设置了| d_e |的新上限。 <10.5×10〜（-28）ecm，置信度为90％。与零一致的结果表明，在这种提高的精度水平上，电子是球形的。我们对分子中电子能量的转移的测量在兆电子能级上探索了新的物理学。

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  • 来源
    《Nature》 |2011年第7348期|p.493-496|共4页
  • 作者

    J. J. Hudson; D. M. Kara; I. J. Smallman; B. E. Sauer; M. R. Tarbutt; E. A. Hinds;

  • 作者单位

    Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK;

    Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK;

    Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK;

    Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK;

    Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK;

    Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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