Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions
Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions
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DOI：
10.1103/physrevlett.115.212003
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发表时间：
2015-11-17
影响因子：
8.6
通讯作者：
Zonta, I.
中科院分区：
文献类型：
--
作者：
Jo, H. S.;Girod, F. X.;Zonta, I.
利用CLAS探测器和杰斐逊实验室加速器的5.75 gev极化电子束，测量了ep -> e'p' γ反应的110 (Q（2), x(B), t）个横截面(d(4)sigma/dQ(2)dx(B)dtd phi)，这是迄今为止在价夸克区探索的最宽相空间。几种广义部分分布（GPDs）模型很好地描述了大多数运动学中的数据。这增加了我们理解GPD H的信心，预计GPD H将是这些可观察到的主要贡献者。通过对康普顿形状因子的前导扭转提取，这些结果支持了在较低夸克动量分数x(B)下较大核子尺寸的模型预测。
Unpolarized and beam-polarized fourfold cross sections (d(4)sigma/dQ(2)dx(B)dtd phi) for the ep -> e'p'gamma reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q(2), x(B), t) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction x(B).