Target normal single-spin asymmetry in inclusive electron-nucleon scattering in the 1/Nc expansion
Target normal single-spin asymmetry in inclusive electron-nucleon scattering in the 1/Nc expansion
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DOI：
10.1103/physrevd.107.094026
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发表时间：
2023-03
影响因子：
5
通讯作者：
J. Goity;C. Weiss;C. Willemyns
中科院分区：
文献类型：
--
作者：
J. Goity;C. Weiss;C. Willemyns
在包含$\Delta$共振的低能区研究了包络电子-核子散射中目标正态单自旋不对称性。对不对称的特别兴趣在于它是由双光子交换效应驱动的。它探测了双光子交换振幅的自旋相关吸收部分，该部分不受红外和共线奇点的影响，代表了双光子交换动力学的最原始表达。本文的研究使用QCD的1/Nc扩展，通过重子扇区中涌现的SU(4)自旋风味对称将$N$和$\Delta$结合起来，并允许系统地构建过渡EM电流。该分析包括1/Nc扩展中的第一次子导修正，并给出了弹性和非弹性最终状态的结果。发现不对称性在$10^{-3}-10^{-2}$的范围内。$\Delta$共振在弹性不对称中作为中间态，在包容不对称中作为最终态发挥着重要作用。
The target normal single-spin asymmetry in inclusive electron-nucleon scattering is studied in the low-energy regime that includes the $\Delta$ resonance. The particular interest in the asymmetry resides in that it is driven by two-photon exchange effects. It probes the spin-dependent absorptive part of the two-photon exchange amplitude, which is free of infrared and collinear singularities and represents the most pristine expression of two-photon exchange dynamics. The study presented here uses the 1/Nc expansion of QCD, which combines the $N$ and $\Delta$ through the emergent SU(4) spin-flavor symmetry in the baryon sector and allows for a systematic construction of the transition EM currents. The analysis includes the first subleading corrections in the 1/Nc expansion and presents results for elastic and inelastic final states. The asymmetry is found to be in the range $10^{-3}-10^{-2}$. The $\Delta$ resonance plays an important role as an intermediate state in the elastic asymmetry and as a final state in the inclusive asymmetry.