Deeply virtual Compton scattering off the neutron
Deeply virtual Compton scattering off the neutron
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DOI：
10.1038/s41567-019-0774-3
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发表时间：
2020-01
期刊：
影响因子：
19.6
通讯作者：
M. Benali;C. Desnault;Malek Mazouz;Z. Ahmed;H. Albataineh;K. Allada;K. Aniol;V. Bellini;W. Boeglin
中科院分区：
文献类型：
--
作者：
M. Benali;C. Desnault;Malek Mazouz;Z. Ahmed;H. Albataineh;K. Allada;K. Aniol;V. Bellini;W. Boeglin
核子(质子和中子)的三维结构嵌入到所谓的广义部分子分布中，这种分布可以从深度虚化的康普顿散射中获得。在这个过程中，通过交换虚拟光子，高能电子被散射出核子。然后，核子内部的一个夸克发出一个高能的真实光子，它携带着夸克的横向位置和纵向动量的信息。通过测量深度虚化的康普顿散射截面，可以提取与广义部分子分布相关的康普顿形状因子。在这里，我们报道了一个未极化的深度虚拟康普顿散射的观测结果。从测量的光子-电产生截面中，我们提取了一个准自由中子和一个相干氚的截面。由于量子色动力学近似的同位旋对称性，我们可以通过结合我们的测量和前人对质子内部结构的探测来确定不同夸克性质对螺旋度守恒的康普顿形状因子的贡献。这些结果促进了我们对核子结构描述的理解，这对于解决质子自旋之谜是很重要的。
The three-dimensional structure of nucleons (protons and neutrons) is embedded in so-called generalized parton distributions, which are accessible from deeply virtual Compton scattering. In this process, a high-energy electron is scattered off a nucleon by exchanging a virtual photon. Then, a highly energetic real photon is emitted from one of the quarks inside the nucleon, which carries information on the quark’s transverse position and longitudinal momentum. By measuring the cross-section of deeply virtual Compton scattering, Compton form factors related to the generalized parton distributions can be extracted. Here, we report the observation of unpolarized deeply virtual Compton scattering off a deuterium target. From the measured photon-electroproduction cross-sections, we have extracted the cross-section of a quasifree neutron and a coherent deuteron. Due to the approximate isospin symmetry of quantum chromodynamics, we can determine the contributions from the different quark flavours to the helicity-conserved Compton form factors by combining our measurements with previous ones probing the proton’s internal structure. These results advance our understanding of the description of the nucleon structure, which is important to solve the proton spin puzzle.