  This PhD Thesis is mainly devoted to the study of hadronic matrix elements of
kaons. Its inner structure can be divided in three parts. In Chapter 3 we
address the issue of quantum corrections in Resonance Chiral Lagrangians with
the aid of the 1/N_c expansion. We compute, as an illustrative example, the
coupling L_10 to one loop. Chapters 4 and 5 are the main body of the present
work and deal with the determination of the relevant parameters in kaon
phenomenology. We give a value for the invariant B_K, the kaon mass difference
and \epsilon_K in a model-independent way, paying special attention to the
issue of scale and scheme independence. In our approach, this is achieved in a
very natural way once matching between long and short distances is ensured. We
end up with a final chapter on the subject of duality violations in the VV-AA
two-point correlator.
