  We discuss, in the framework of perturbative QCD at next to leading order,
two related observables which are usually considered to provide tests of the
BFKL dynamics : jet-jet correlations at Tevatron energies and forward
particle-jet correlations at HERA. In the first case we study the rapidity gap
dependence of the azimuthal correlations and find slightly too strong
correlations at large gap. In the second case we discuss the cross section as
well as the azimuthal correlations over a rapidity gap range of 5 units. We
find that the requirement of a forward particle imposes strong kinematical
constraints which distort the distributions, notably at small rapidity gaps. We
also show that the decorrelation is stronger in electroproduction than in
hadron-hadron collisions. Unfortunately no data are yet available for
comparison.
