Two-photon-exchange effects in ep→enπ+ and their corrections to separated cross sections σL,T,LT,TT at small −t
Two-photon-exchange effects in ep→enπ+ and their corrections to separated cross sections σL,T,LT,TT at small −t
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DOI：
10.1103/physrevc.101.055201
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发表时间：
2019-10
影响因子：
3.1
通讯作者：
Hui-Yun Cao;Hai-Qing Zhou
中科院分区：
文献类型：
--
作者：
Hui-Yun Cao;Hai-Qing Zhou
本文在一个强子模型中讨论了小$-t$中$ep\rightarrow en\pi^+$的双光子交换（TPE）效应。估计了TPE对振幅和非极化微分截面的贡献，并发现TPE对非极化微分截面的修正约为$-4\%\sim-15\%$ （$Q^2=1$ GeV $^2\sim1.6$ GeV $^2$）。在考虑了对非偏振微分截面实验数据集的TPE校正后，我们分析了对分离截面的TPE校正$\sigma_{\textrm{L,T,LT,TT}}$。我们发现TPE修正（在$Q^2=1$ GeV $^2\sim1.6$ GeV $^2$）到$\sigma_{\textrm{L}}$大约是$-10\%\sim -20\%$，到$\sigma_{\textrm{T}}$大约是$20\%$，到$\sigma_{\textrm{LT,TT}}$要大得多。通过这些分析，我们得出结论，$ep\rightarrow en\pi^+$在小$-t$处的TPE贡献对于提取分离截面$\sigma_{\textrm{L,T,LT,TT}}$和实验分析中$\pi^+$的电磁形状因子是重要的。
In this work, the two-photon-exchange (TPE) effects in $ep\rightarrow en\pi^+$ at small $-t$ are discussed within a hadronic model. The TPE contributions to the amplitude and the unpolarized differential cross section are both estimated and we find that the TPE corrections to the unpolarized differential cross section are about $-4\%\sim-15\%$ at $Q^2=1$GeV$^2\sim1.6$GeV$^2$. After considering the TPE corrections to the experimental data sets of unpolarized differential cross section, we analyse the TPE corrections to the separated cross sections $\sigma_{\textrm{L,T,LT,TT}}$. We find that the TPE corrections (at $Q^2=1$GeV$^2\sim1.6$GeV$^2$) to $\sigma_{\textrm{L}}$ are about $-10\%\sim -20\%$, to $\sigma_{\textrm{T}}$ are about $20\%$ and to $\sigma_{\textrm{LT,TT}}$ are much larger. By these analysis, we conclude that the TPE contributions in $ep\rightarrow en\pi^+$ at small $-t$ are important to extract the separated cross sections $\sigma_{\textrm{L,T,LT,TT}}$ and the electromagnetic magnetic form factor of $\pi^+$ in the experimental analysis.