论文标题
不连贯的虚拟康普顿分散$^4 $ He
Incoherent deeply virtual Compton scattering off $^4$He
论文作者
论文摘要
最近，这是第一次使用$^4 $ HE TORAND的CLAS协作，这两个核核对虚拟的康普顿散射（DVC）（DVC）已被JLAB的CLAS合作所分开。不一致的通道可以在脉冲近似（IA）中对其难以捉摸的Parton结构提供构造质子的层析成像视图，并阐明了其难以捉摸的Parton结构。跨部分的卷积公式是根据结合质子的。已经获得并使用了结合运动核的新型散射幅度。基于AV18电位的最先进的核光谱函数在两体部分中精确，其接回系统处于基础状态，并以剩余贡献进行建模，并以激发状态的后退系统进行了模型。已测试了质子的普通Parton分布的不同参数化。与梁自旋不对称（BSA）的数据达到了良好的总体一致性。发现预测的常规核效应与DVC和竞争性的伯特人机制相关，但它们在很大程度上相互抵消，其比例与测量的不对称性是比例的。此外，结合质子的BSA与自由质子的BSA的计算比率并未描述由实验协作估计的。这表明除了此处介绍的IA分析之外，可能的有趣效果。因此，清楚地证明，与未来的精确数据相比，传统现实方法的结果的比较有可能暴露核中夸克和gluon效应。在高光度设施上进行下一个测量的有趣观点，例如JLAB在12 GEV和Future EIC。
Very recently, for the first time, the two channels of nuclear deeply virtual Compton scattering (DVCS), the coherent and incoherent ones, have been separated by the CLAS collaboration at JLab, using a $^4$He target. The incoherent channel, which can provide a tomographic view of the bound proton and shed light on its elusive parton structure, is thoroughly analyzed here in Impulse Approximation (IA). A convolution formula for the cross sections in terms of those for the bound proton is derived. Novel scattering amplitudes for a bound moving nucleon have been obtained and used. A state-of-the-art nuclear spectral function, based on the AV18 potential, exact in the two-body part, with the recoiling system in its ground state, and modelled in the remaining contribution, with the recoiling system in an excited state, has been used. Different parametrizations of the generalized parton distributions of the struck proton have been tested. A good overall agreement with the data for the beam spin asymmetry (BSA) is obtained. It is found that the predicted conventional nuclear effects are relevant in DVCS and in the competing Bethe-Heitler mechanism, but they cancel each other to a large extent in their ratio, to which the measured asymmetry is proportional. Besides, the calculated ratio of the BSA of the bound proton to that of the free one does not describe that estimated by the experimental collaboration. This points to possible interesting effects beyond the IA analysis presented here. It is therefore clearly demonstrated that the comparison of the results of a conventional realistic approach, as the one presented here, with future precise data, has the potential to expose quark and gluon effects in nuclei. Interesting perspectives for the next measurements at high luminosity facilities, such as JLab at 12 GeV and the future EIC, are addressed.
