  The phenomenology of hadronic states at high energy is well described in the
framework of Quantum Chromodynamics. The theory, well established by now,
cannot be applied to the description of quark-antiquark states at low energy
unless their degrees of freedom are treated as effective ones, a condition
resulting from confinement. Own to the similarities with other quantum
many-body systems we have adopted a non-perturbative scheme where quarks are
treated as quasiparticles, which further interact between them, allowing
meson-like states to be described as collective superposition of
quasiparticle-pairs. The results of the calculations, performed in the context
of the random phase approximation method, show that this scheme is a suitable
one to describe meson states up to energies of the order of couple of GeV.
