Description
We studied the diffractive photoproduction of $J/\psi$ mesons at the highest available energies.The data from ultraperipheral collisions (UPCs) are well described at high energies/small-$x$ after including additional shadowing from the $c \bar c g$ Fock state.
We confront our results on diffractive photoproduction of $J/\psi$ mesons with the putative gluon shadowing ratio defined as $R_g= \sqrt{\sigma(\gamma A \to J/\psi A)/\sigma_{\rm IA.}}$, where $\sigma_{\rm IA}$ is the result in impulse approximation.
Building on our earlier description of the process in the color-dipole approach, where we took into account the rescattering of $c \bar c$ states only, we demonstrate that the inclusion of $c \bar c g$-Fock states improves the description at small $x$ commonly associated with gluon shadowing. The results are published in Phys.Lett.B 856 (2024) 138917.
| Secondary track | T04 - Ultra-relativistic Nuclear Collisions |
|---|
