Baryons from instantons in holographic QCD

TL;DR

This paper models baryons in holographic QCD as instanton solutions in a D4/D8-brane setup, deriving baryon spectra including negative-parity and higher-spin states through collective coordinate quantization.

Contribution

It constructs a soliton solution representing baryons as instantons in holographic QCD, highlighting the role of the Chern-Simons term in stabilizing the instanton size.

Findings

Constructed a baryon soliton as an instanton with fixed size.

Derived baryon spectra including negative-parity and higher-spin states.

Showed the importance of the Chern-Simons term in stabilizing the instanton.

Abstract

We consider aspects of dynamical baryons in a holographic dual of QCD that is proposed on the basis of a D4/D8-brane configuration. We construct a soliton solution carrying a unit baryon number and show that it is given by an instanton solution of four-dimensional Yang-Mills theory with fixed size. The Chern-Simons term on the flavor D8-branes plays a crucial role of protecting the instanton from collapsing to zero size. By quantizing the collective coordinates of the soliton, we work out the baryon spectra. Negative-parity baryons as well as baryons with higher spins and isospins can be obtained in a simple manner.