Comments on baryons in holographic QCD

Abstract

We generalize the description of baryons as instantons of Sakai-Sugimoto model to the case where the flavor branes are non-anti-podal. The later corresponds to quarks with a ``string endpoint mass''. We show that the baryon vertex is located on the flavor branes and hence the generalized baryons also associate with instantons. We calculate the baryon mass spectra, the isoscalar and axial mean square radii, the isoscalar and isovector magnetic moments and the axial coupling as a function of the mass scaleMKK and the location ζ of the tip of U-shaped flavor D8-branes. We determine the values of MKK and ζ from a best fit comparison with the experimental data. The later comes out to be in a forbidden region, which may indicate that the incorporation of baryons in Sakai-Sugimoto model has to be modified. We discuss the analogous baryons in a non-critical gravity model. A brief comment on the single flavor case (Nf = 1) is also made.