A new global Bayesian analysis has successfully reconciled measurements of diffractive J/ψ photoproduction in photon-proton (γ+p) and photon-lead (γ+Pb) collisions. This breakthrough, based on the Color Glass Condensate (CGC) theoretical framework, addresses a persistent discrepancy between data obtained from colliders such as HERA and the Large Hadron Collider (LHC).

The research utilized ultraperipheral collision data from the LHC, correcting for the expected effect of electromagnetic dissociation (EMD). By employing Gaussian-process emulators for the complex CGC calculations, scientists were able to infer model parameters from a combined set of HERA and LHC measurements. The EMD correction in the γ+Pb data proved crucial, significantly reducing the previously observed tension between proton and nuclear datasets.

This study demonstrates the CGC framework's ability to consistently and simultaneously describe diffractive J/ψ production in both types of collisions. The reconciliation of these experimental data strengthens the validity of the CGC model, which is fundamental for understanding gluon dynamics within hadrons and nuclei at high energies, a regime where gluon density is so high that saturation is expected. This work opens new avenues for exploring the internal structure of nuclear matter under extreme conditions.