Tomography of Ultra-relativistic Nuclei with Polarized Photon-gluon Collisions

Understand

A linearly polarized photon can be quantized from the Lorentz-boosted electromagnetic field of a nucleus traveling at ultra-relativistic 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.
• ${\rho^0}$).
• In this experiment, the polarization was utilized in diffractive photoproduction to observe a unique spin interference pattern in the angular distribution of ${\rho^0\rightarrow\pi^+\pi^-}$ decays.