Sci Adv. 2023 Jan 4;9(1):eabq3903. doi: 10.1126/sciadv.abq3903.
A linearly polarized photon can be quantized from the Lorentz-boosted electromagnetic field of a nucleus traveling at ultrarelativistic speed. When two relativistic heavy nuclei pass one another at a distance of a few nuclear radii, the photon from one nucleus may interact through a virtual quark-antiquark pair with gluons from the other nucleus, forming a short-lived vector meson (e.g., ρ). In this experiment, the polarization was used in diffractive photoproduction to observe a unique spin interference pattern in the angular distribution of ρ → ππ decays. The observed interference is a result of an overlap of two wave functions at a distance an order of magnitude larger than the ρ travel distance within its lifetime. The strong-interaction nuclear radii were extracted from these diffractive interactions and found to be 6.53 ± 0.06 fm (Au) and 7.29 ± 0.08 fm (U), larger than the nuclear charge radii. The observable is demonstrated to be sensitive to the nuclear geometry and quantum interference of nonidentical particles.
一个线偏振光子可以从以超相对论速度运动的原子核的洛伦兹增强电磁场中量子化。当两个相对论重核以几个核半径的距离彼此通过时，一个核的光子可能通过一个虚拟的夸克-反夸克对与另一个核的胶子相互作用，形成一个短寿命的矢量介子（例如，ρ）。在这个实验中，极化被用于研究散射光生产，以观察到 ρ→ππ衰变的角分布中的一个独特的自旋干涉模式。观察到的干涉是两个波函数在距离上的重叠的结果，这个距离比 ρ 在其寿命内的传播距离大一个数量级。从这些散射相互作用中提取出强相互作用的核半径，发现 Au 的核半径为 6.53±0.06fm，U 的核半径为 7.29±0.08fm，比核电荷半径大。该可观测量被证明对核几何形状和不同粒子的量子干涉敏感。
