  The AdS/QCD models suggest an interesting idea that the effective theory of
low-energy QCD may be formulated as a 5-dimensional field theory in the weak
coupling regime in which the fifth coordinate plays a role of inverse energy
scale. Taking the point of view that this is just an efficient parametrization
of the non-perturbative dynamics of strong interactions, we discuss on a
qualitative level an alternative possibility for a simpler 5-dimensional
parametrization of main phenomena in the low-energy QCD. We propose to
interpret the effect of chiral symmetry breaking as an effective appearance of
compactified extra dimension with the radius of the order of inverse scale of
chiral symmetry breaking. Following some heuristic arguments two dual scenarios
for the emergence of the excited light mesons are introduced: In the first
scenario, the meson resonances are interpreted as the effects of Kaluza-Klein
excitations of quarks inside mesons, in the second one, as the formation of
gluon strings wound around the compactified dimension an appropriate number of
times. Matching of these scenarios permits to express the slope of radial Regge
trajectories through the order parameters of the chiral symmetry breaking, with
the compactification radius being excluded. This example shows qualitatively
that the extra dimension may play an auxiliary role providing a short way for
deriving new relations.
