  We study jet physics in the high energy regime of QCD. Based on the NLO BFKL
equation, we construct a vertex for the production of a jet at central rapidity
in k_T-factorization. A jet algorithm is introduced, and we take special care
of the separation of multi-Regge and quasi-multi-Regge kinematics. The
connection with the energy scale of the evolution is investigated in detail.
The result is discussed for two situations: scattering of highly virtual
photons, which requires a symmetric energy scale to separate the impact factors
from the gluon Green's function, and hadron-hadron collisions, where a
non-symmetric scale choice is needed. For the second case we are able to define
a NLO unintegrated gluon density, valid in the small-x regime, and give the
evolution equation for this density as well.
  In the second part, we examine the angular decorrelation of Mueller-Navelet
jets. Using an operator formalism in the space of anomalous dimension and
conformal spin, we implement the NLO BFKL Green's function to study the
rapidity dependence of angular decorrelations. We incorporate the necessary
summation of collinearly enhanced corrections beyond NLO accuracy. We compare
our results with data from the Tevatron ppbar-collider and provide predictions
for the LHC as well. We also extend our study to the angular decorrelation
between a forward jets and the electron in deep inelastic ep scattering. The
angular decorrelation has not been measured in DIS so far, but we give
theoretical results for this observable which already implement the
experimental cuts.
