  The spectrum of radially excited hadrons provides much information about the
confinement forces in QCD. The confinement is realized most naturally in terms
of the QCD string whose quantization gives rise to the radially excited modes.
We propose an alternative framework for the description of the excited
spectrum. Namely we put forward some effective field models in which the
hadrons acquire masses due to interaction with a scalar field modeling the
non-perturbative gluon vacuum. The effective potential for this field is
periodic with an infinite number of non-equivalent vacua. The radially excited
hadrons emerge as elementary excitations over different vacua. We construct
explicit examples for such effective theories in the meson sector. An
interesting byproduct of the considered models is the existence of a classical
field configuration in each vacuum. Depending on the model, it can represent a
domain wall, Nielsen-Olesen vortex or 't Hooft-Polyakov monopole. In the pure
scalar sector, it is shown that the first quantum correction leads to splitting
of the radially excited modes into two nearly degenerate states. Such a
phenomenon has some phenomenological support. The presented approach may be
also viewed as an alternative framework to the bottom-up AdS/QCD models where
the radial excitations appear on the classical level as well.
