  In this thesis, we calculate diffractive processes at next-to-leading order
(NLO) in the high-energy limit, with an emphasis on exclusive vector meson
production and inclusive diffraction in deep inelastic scattering (DIS).
Calculations in the high-energy limit can be done using the dipole picture, the
basics of which are briefly reviewed. This includes using the color-glass
condensate effective field theory to describe the nonperturbative dipole-target
scattering amplitude which appears in practically all calculations in the
dipole picture. The universality of the dipole-target scattering amplitude at
NLO is shown numerically, in the sense that the same dipole-target scattering
amplitude can be used to describe the data in both massless and massive quark
production in inclusive DIS, and also in diffractive processes where exclusive
vector meson production is considered. The analytical NLO calculations of
exclusive vector meson production and inclusive diffraction in DIS are also
explained. Exclusive vector meson production is calculated in the
nonrelativistic limit for heavy mesons and the limit of large photon virtuality
for light mesons. Also, the importance of including relativistic corrections to
the heavy vector meson wave function in exclusive vector meson production is
considered. For inclusive diffraction in DIS, we focus on the NLO corrections
to the final state and show how the divergences cancel.
