  According to the conjecture of the gauge/gravity duality a strongly coupled
4D field theory may be described by a dual 5D theory which is a free field
theory in the first approximation. The usual description of the axial-vector
sector in the bottom-up AdS/QCD models includes, however, the quartic
interaction with a bulk scalar field. The question appears whether it is
possible to describe some aspects of the chiral symmetry breaking in a way more
consistent with the original proposal, i.e. within a free 5D theory? We suggest
that a natural candidate for this purpose is the soft-wall model with inverse
exponential profile.
