  We study baryons as Skyrmions in holographic QCD with D4/D8/D8-bar multi-D
brane system in type IIA superstring theory, and also in the non-linear sigma
model with hidden local symmetry (HLS). Comparing these two models, we find
that the extra-dimension and its nontrivial curvature can largely change the
role of (axial) vector mesons for baryons in four-dimensional space-time. In
the HLS approach, the rho-meson field as a massive Yang-Mills field has a
singular configuration in Skyrmion, which gives a strong repulsion for the
baryon as a stabilizer. When a_1 meson is added in this approach, the stability
of Skyrmion is lost by the cancellation of rho and a_1 contributions. On the
contrary, in holographic QCD, the rho-meson field does not appear as a massive
Yang-Mills field due to the extra-dimension and its nontrivial curvature. We
show that the rho-meson field has a regular configuration in Skyrmion, which
gives a weak attraction for the baryon in holographic QCD. We argue that
Skyrmion with pi, rho and a_1 mesons become stable due to the curved
extra-dimension and also the presence of the Skyrme term in holographic QCD.
  From this result, we also discuss the features of our truncated-resonance
analysis on baryon properties with pi and rho mesons below the cutoff scale
M_KK about 1GeV in holographic QCD, which is compared with other 5D instanton
analysis.
