论文标题
关于D参数对新物理的敏感性
On the sensitivity of the D parameter to new physics
论文作者
论文摘要
核β衰减中角相关性的测量是标准模型（SM）的重要测试。其中，所谓的D相关参数占据了一个特定的位置，因为它在时间逆转下是奇怪的，并且由于实验灵敏度为$ 10^{ - 4} $级别，并计划在不久的将来进一步改善。使用有效的现场理论（EFT）技术，我们重新评估其潜力，以发现或限制SM超出SM的新物理学。我们提供了CP侵略EFT方案的全面分类，该方案从SM预测中产生了D参数的转移。我们表明，在每种情况下，大于$ 10^{ - 5} $的偏移与现有的实验数据非常紧张，其中来自电动偶极矩和LHC可观测值的界限起决定性的作用。只有通过在EFT的紫外线完成中对参数的微调才能避免张力。我们使用Leptoquark UV完成的示例来说明这一点。最后，我们评论通过D参数探测新物理的可能性。
Measurements of angular correlations in nuclear beta decay are important tests of the Standard Model (SM). Among those, the so-called D correlation parameter occupies a particular place because it is odd under time reversal, and because the experimental sensitivity is at the $10^{-4}$ level, with plans of further improvement in the near future. Using effective field theory~(EFT) techniques, we reassess its potential to discover or constrain new physics beyond the SM. We provide a comprehensive classification of CP-violating EFT scenarios which generate a shift of the D parameter away from the SM prediction. We show that, in each scenario, a shift larger than $10^{-5}$ is in serious tension with the existing experimental data, where bounds coming from electric dipole moments and LHC observables play a decisive role. The tension can only be avoided by fine tuning of the parameters in the UV completion of the EFT. We illustrate this using examples of leptoquark UV completions. Finally, we comment on the possibility to probe CP-conserving new physics via the D parameter.
