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arXiv 1809.07413hep-ph
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介子在μ g-2中的作用

The Role of Mesons in Muon g-2

Fred Jegerlehner

摘要:

μ子异常$a_μ=(g_μ-2)/2$显示出SM预测和实验之间持续3到4个$σ$偏差,这是SM之外物理学最有希望的信号之一。众所周知,强子的不确定性限制了标准模型预测的准确性。因此,一个大的努力正在进行,以改善强子效应的评估,以跟上4倍的提高精度预期从新的费米实验室测量在不久的将来。日本J-PARC计划进行一项新的互补型实验,使用超冷μ子,预计能够达到相同的精度,但系统学完全不同。因此,寻找新物理学的激动人心的时刻正在进行中。我讨论介子物理学在μ介子g-2的强子部分的计算中的作用。如果强子不确定性可以减少到原来的两倍,那么这种改进有望使目前的偏差$Δa_μ^{\rm New \ Physics}=Δa_μ^{\rm Experiment}- Δa_μ^{\rm Standard \ Model}$达到6到10个标准偏差的效果。这涉及到强子真空极化以及强子光-光散射的贡献,两者在很大程度上都由低位介子谱决定。更好的介子产生数据和介子形状因子建模的进展可以极大地帮助提高$a_μ$的SM预测的精度和可靠性,从而提供更多关于SM中缺失的信息。

英文摘要:

The muon anomaly $a_μ=(g_μ-2)/2$ showing a persisting 3 to 4 $σ$ deviation between the SM prediction and the experiment is one of the most promising signals for physics beyond the SM. As is well known, the hadronic uncertainties are limiting the accuracy of the Standard Model prediction. Therefore a big effort is going on to improve the evaluations of hadronic effects in order to keep up with the 4-fold improved precision expected from the new Fermilab measurement in the near future. A novel complementary type experiment planned at J-PARC in Japan, operating with ultra cold muons, is expected to be able to achieve the same accuracy but with completely different systematics. So exciting times in searching for New Physics are under way. I discuss the role of meson physics in calculations of the hadronic part of the muon g-2. The improvement is expected to substantiate the present deviation $Δa_μ^{\rm New \ Physics}=Δa_μ^{\rm Experiment}- Δa_μ^{\rm Standard \ Model}$ to a 6 to 10 standard deviation effect, provided hadronic uncertainties can be reduce by a factor two. This concerns the hadronic vacuum polarization as well as the hadronic light-by-light scattering contributions, both to a large extent determined by the low lying meson spectrum. Better meson production data and progress in modeling meson form factors could greatly help to improve the precision and reliability of the SM prediction of $a_μ$ and thereby provide more information on what is missing in the SM.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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