  This Ph.D.~thesis is divided into two distinct parts. The first part focuses
on hard exclusive scattering processes in Quantum Chromodynamics (QCD) at high
energies, while the second part delves into spin phenomena at the Large Hadron
Collider (LHC).
  Hard exclusive scattering processes play a crucial role in QCD at high
energies, providing unique insights into the confined partonic dynamics within
hadrons, complementing inclusive processes. Studying these processes within the
QCD factorization approach yields the generalized parton distribution (GPD), a
nonperturbative parton correlation function that offers a three-dimensional
tomographic parton image within a hadron. However, the experimental measurement
of these processes poses significant challenges. This thesis will review the
factorization formalism for related processes, examine the limitations of some
widely used processes, and introduce two novel processes that enhance the
sensitivity to GPD, particularly its dependence on the parton momentum fraction
$x$.
  The second part of the thesis centers on spin phenomena, specifically single
spin production, at the LHC. Noting that a single transverse polarization can
be generated even in an unpolarized collision, this research proposes two new
jet substructure observables: one for boosted top quark jets and another for
high-energy gluon jets. The observation of these phenomena paves the way for
innovative tools in LHC phenomenology, enabling both precision measurements and
the search for new physics.
