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Photonuclear processes have been understood for decades to be a golden channel for performing tomography of the gluon density and spatial distribution within nucleons and nuclei. However, measurements of the nuclear mass radii of Gold and Lead nuclei from photonuclear processes in ultra-relativistic A+A collisions have produced unexplainably large values, inconsistent with low-energy results and theoretical expectations. This puzzle persisted for two decades without resolution until the discovery of the Breit-Wheeler process shed new light on this confounding situation by demonstrating that the photons manifest from ultra-Lorentz contracted electromagnetic field are linearly polarized. In photonuclear A+A interactions, the polarization (spin) of the coherent photons turns out to be a crucial ingredient. In this talk I will present a unique spin interference pattern in the angular distribution of rho meson decays from diffractive photonuclear interactions. The observed interference is a result of an overlap of two wave functions at a distance an order of magnitude larger than the rho meson travel distance within its lifetime - requiring that any interference occur between the daughter particles. Crucially, this novel type of quantum interference between distinguishable particles is only possible when the particles are entangled. Next, I will discuss how this entanglement-enabled spin interference (EESI) effect resolves the 20-year puzzle of unreasonably large nuclear radii extracted from photonuclear A+A interactions. The newfound sub-femtoscale precision of the EESI technique is demonstrated through the first high-energy measurement of the nuclear mass radii and the neutron skins of Gold and Uranium nuclei. Finally, I will discuss applications of this new technique for further probing gluon dynamics within large nuclei at RHIC and the future Electron Ion Collider.
Zoom link: https://bnl.zoomgov.com/j/1605020278?pwd=cHJ1bDRuK1FDNnZLSnpxVkZhcDQ3QT09