Speaker
Description
The charmonium photoproduction near threshold can be used to study important aspects of the gluon structure of the proton, such as the gluon Generalized Parton Distribution (GPD), the gravitational form factors, the mass radius of the proton, and the anomalous contribution to the proton mass. However, such an ambitious program requires precise measurements over the full kinematic range to validate the theoretical assumptions that relate the experimental results to the above quantities. We report the total and differential cross sections for $J/\psi$ photoproduction with the large acceptance GlueX spectrometer for photon beam energies from the threshold of $8.2$ GeV up to $11.44$ GeV and over the full kinematic range of momentum transfer squared, $t$. Such measurements enable more general conclusions about the reaction mechanism when compared to a wide range of theoretical predictions including GPD calculations and models with open-charm intermediate states. Photoproduction of higher-mass charmonium states near threshold will be discussed, as well.
