  The main motivation is to investigate meson properties in the quark model to
understand the model applicability and generate possible improvements. Certain
modifications to the model are suggested which have been inspired by
fundamental QCD properties (such as running coupling or spin dependence of
strong interactions). These modifications expand the limits of applicability of
the constituent quark model and illustrate its weaknesses and strengths. The
meson properties studied include meson spectra, decay constants,
electromagnetic and electroweak form-factors and radiative transitions. The
results are compared to the experimental data, lattice gauge theory
calculations and other approaches. Modifications to the quark model suggested
in this dissertation lead to a very good agreement with available experimental
data and lattice results.
