Oscillating features in the electromagnetic structure of the neutron
Oscillating features in the electromagnetic structure of the neutron
复制标题
中子电磁结构的振荡特征
DOI：
10.1038/s41567-021-01345-6
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发表时间：
2021-11-01
期刊：
影响因子：
19.6
通讯作者：
Zou, J. H.
中科院分区：
文献类型：
--
作者：
Ablikim, M.;Achasov, M. N.;Zou, J. H.
由于夸克的色荷和胶子的自相互作用，中子的复杂结构不能用第一性原理计算。它最简单的结构观测是电磁形状因子，它探索了我们对强相互作用的理解。到目前为止，从类时运动学范围确定中子结构的数据还很少。在这里，我们提出了测量的玻恩截面的电子-正电子湮没反应成一个中子和反中子对，并确定中子的有效形状因子。这些数据是由BESIII实验在质心能量为2.00至3.08 GeV之间，积分光度为647.9 pb−1时记录的。我们的研究结果提高了统计的中子形状因子的一个以上的60比以前的测量的因素，表明在类时制度的湮灭中子形状因子的数据是等同于从电子散射实验。中子的有效形状因子显示出周期性的行为，类似于早期对质子形状因子的观测。未来的工作，无论是理论和实验，将有助于阐明这种振荡的电磁结构的核子观测值的起源。
The complicated structure of the neutron cannot be calculated using first-principles calculations due to the large colour charge of quarks and the self-interaction of gluons. Its simplest structure observables are the electromagnetic form factors, which probe our understanding of the strong interaction. Until now, a small amount of data has been available for the determination of the neutron structure from the time-like kinematical range. Here we present measurements of the Born cross section of electron–positron annihilation reactions into a neutron and anti-neutron pair, and determine the neutron’s effective form factor. The data were recorded with the BESIII experiment at centre-of-mass energies between 2.00 and 3.08 GeV using an integrated luminosity of 647.9 pb−1. Our results improve the statistics on the neutron form factor by more than a factor of 60 over previous measurements, demonstrating that the neutron form factor data from annihilation in the time-like regime is on par with that from electron scattering experiments. The effective form factor of the neutron shows a periodic behaviour, similar to earlier observations of the proton form factor. Future works—both theoretical and experimental—will help illuminate the origin of this oscillation of the electromagnetic structure observables of the nucleon.