Baryons in holographic QCD

We study baryons in holographic QCD with D4/D8/(D8) over bar multi-D-brane system. In holographic QCD, the baryon appears as a topologically nontrivial chiral soliton in a four-dimensional effective theory of mesons. We call this topological soliton brane-induced Skyrmion. Some review of D4/D8/(D8) over bar holographic QCD is presented from the viewpoints of recent hadron physics and QCD phenomenologies. A four-dimensional effective theory with pions and rho mesons is uniquely derived from the non-Abelian Dirac-Born-Infeld (DBI) action of D8 brane with D4 supergravity background at the leading order of large N-c, without small amplitude expansion of meson fields to discuss chiral solitons. For the hedgehog configuration of pion and rho-meson fields, we derive the energy functional and the Euler-Lagrange equation of brane-induced Skyrmion from the meson effective action induced by holographic QCD. Performing the numerical calculation, we obtain the soliton solution and figure out the pion profile F(r) and the rho-meson profile (G) over tilde (r) of the brane-induced Skyrmion with its total energy, energy density distribution, and root-mean-square radius. These results are compared with the experimental quantities of baryons and also with the profiles of standard Skyrmion without rho mesons. We analyze interaction terms of pions and rho mesons in brane-induced Skyrmion, and find a significant rho-meson component appearing in the core region of a baryon.