Holographic QCD and pion mass

To realize massive pions, we study variations of the holographic model of massless QCD using the D4/D8/(D8) over bar brane configuration proposed by Sakai and Sugimoto. We propose deformations which break the chiral symmetry explicitly and compute the mass of the pions and vector mesons. The observed value of the pion mass can be obtained. We also argue a chiral perturbation corresponding to our deformation.