Meson exchange effects in elastic ep scattering at loop level and the electromagnetic form factors of the proton
Meson exchange effects in elastic ep scattering at loop level and the electromagnetic form factors of the proton
复制标题
环级弹性ep散射中的介子交换效应和质子的电磁形状因子
DOI：
10.1103/physrevc.90.045205
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发表时间：
2013-12
影响因子：
3.1
通讯作者：
Zhou Hai-Qing
中科院分区：
文献类型：
--
作者：
Chen Hong-Yu;Zhou Hai-Qing
研究了一种新的双光子交换（TPE）效应，以解释弹性极电位散射中非极化和极化实验数据的差异。该机制是基于一个简单的想法，即除了通常的盒状图和交叉盒状图中的TPE效应外，介子也可以在环路水平上通过双光子耦合在弹性极电散射中交换。详细的研究表明，在固定Q(2)下，这种对减少的非极化截面（sigma(un)）和极化观测值（p -t, p -l）的贡献仅取决于质子的电磁形状因子G（E，M）和一个新的未知通用参数G。将这种贡献与通常的盒状图和交叉盒状图的TPE贡献结合起来，可以一致地描述从最近精确的非极化和极化实验数据中提取的比率mu(p)G(E)/G(M)。
A new form of two-photon exchange (TPE) effect is studied to explain the discrepancy between unpolarized and polarized experimental data in elastic ep scattering. The mechanism is based on a simple idea that apart from the usual TPE effects from box and crossed-box diagrams, the mesons may also be exchanged in elastic ep scattering by two-photon coupling at loop level. The detailed study shows such contributions to reduced unpolarized cross section (sigma(un)) and polarized observables (P-t, P-l) at fixed Q(2) are only dependent on proton's electromagnetic form factors G(E,M) and a new unknown universal parameter g. After combining this contribution with the usual TPE contributions from box and crossed-box diagrams, the ratio mu(p)G(E)/G(M) extracted from the recent precise unpolarized and polarized experimental data can be described consistently.