低能与高能康普顿散射中的光子-核子纠缠
Photon-nucleon entanglement in Compton scattering at low and high energies
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中文总结 AI 辅助
该研究通过分析低能与高能康普顿散射，证明非极化康普顿散射在散射振幅为实数时无法产生光子-核子纠缠，发现极化散射中质子与中子的纠缠模式存在差异，提出纠缠可作为研究核子电磁性质的工具。
中文摘要 AI 辅助
我们研究康普顿散射末态光子-核子系统中的自旋-自旋纠缠，涵盖低于π介子阈值的低能区域与微扰量子色动力学下的次领头阶高能区域。首先，我们证明了一个“不可能定理”：对于任意自旋为1/2的靶，若散射振幅为实数，则非极化康普顿散射无法产生纠缠。随后，我们研究电子、质子和中子靶的极化康普顿散射。在低能区域，我们发现运动学平面不同区域存在多种最大纠缠的贝尔态及其幺正等价态；值得注意的是，质子与中子靶呈现出截然不同的纠缠模式。对于中子，电与磁极化率会显著影响纠缠模式甚至其存在性，这表明纠缠可作为研究核子详细电磁性质的新型工具。
英文摘要
We study spin-spin entanglement in the final state photon-nucleon system in Compton scattering, both at low energy below the pion threshold and at high energy in perturbative QCD to next-to-leading order. We first establish a no-go theorem showing that, for any spin-$\frac{1}{2}$ target, entanglement cannot be generated in unpolarized Compton scattering if the scattering amplitudes are real. We then consider polarized Compton scattering off the electron, the proton and the neutron. At low energy, we uncover a rich variety of maximally entangled Bell states and their unitary equivalents realized across different regions of the kinematic plane. Interestingly, the proton and neutron targets exhibit distinct patterns of entanglement. In the neutron case, the electric and magnetic polarizabilities dramatically influence the pattern and even the existence of entanglement. This suggests that entanglement can serve as a novel tool for investigating the detailed electromagnetic properties of the nucleons.
