SciPost Phys. Proc. 8, 133 (2022) ·
published 14 July 2022
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We present results for higher-order corrections to exclusive
$\mathrm{J}/\psi$ production. This includes the first relativistic correction
of order $v^2$ in quark velocity, and next-to-leading order corrections in
$\alpha_s$ for longitudinally polarized production. The relativistic
corrections are found to be important for a good description of the HERA data,
especially at small values of the photon virtuality. The next-to-leading order
results for longitudinal production are evaluated numerically. We also
demonstrate how the vector meson production provides complementary information
to the structure functions for extracting the initial condition for the
small-$x$ evolution of the dipole-proton scattering amplitude.
