Comments on Baryons in Holographic QCD

TL;DR

This paper extends the holographic QCD model to include non-anti-podal flavor branes, calculates baryon properties, and compares them with experimental data, revealing potential limitations of the current model.

Contribution

It generalizes baryon descriptions in the Sakai-Sugimoto model to non-anti-podal branes and analyzes resulting physical properties and parameter fits.

Findings

Baryon mass spectra are computed as functions of model parameters.

The best-fit parameters fall into a forbidden region, indicating model limitations.

Discussion of baryons in a non-critical gravity framework.

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 scale M_{KK} and the location \zeta of the tip of U-shaped flavor D8-branes. We determine the values of M_{KK} and \zeta 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 (N_f=1) is also made.