  In the Wick-Cutkosky model, where two scalar massive constituents interact by
means of the exchange of a scalar massless particle, the Bethe-Salpeter
equation has solutions of two types, called "normal" and "abnormal". In the
non-relativistic limit, the normal solutions correspond to the usual Coulomb
spectrum, whereas the abnormal ones do not have non-relativistic counterparts
-- they are absent in the Schr\"odinger equation framework. We have studied, in
the formalism of the light-front dynamics, the Fock-space content of the
abnormal solutions. It turns out that, in contrast to the normal ones, the
abnormal states are dominated by the massless exchange particles (by 90 \% or
more), what provides a natural explanation of their decoupling from the
two-body Schr\"odinger equation. Assuming that one of the massive constituents
is charged, we have calculated the electromagnetic elastic form factors of the
normal and abnormal states, as well as the transition form factors. The results
on form factors confirm the many-body nature of the abnormal states, as found
from the Fock-space analysis. The abnormal solutions have thus properties
similar to those of hybrid states, made here essentially of two massive
constituents and several or many massless exchange particles. They could also
be interpreted as the Abelian scalar analogs of the QCD hybrid states. The
question of the validity of the ladder approximation of the model is also
examined.
