The Skyrmion strikes back: baryons and a new large $N_c$ limit

TL;DR

This paper explores a new large $N_c$ limit in QCD, demonstrating that baryons can be modeled as solitons with different scaling behaviors, offering an alternative perspective to traditional approaches.

Contribution

It introduces and analyzes the orientifold large $N_c$ limit, showing how baryons and solitons behave differently compared to the traditional large $N_c$ limit.

Findings

Baryons can be identified as solitons in the orientifold large $N_c$ limit.

Interaction amplitudes scale with $N_c^{-1}$, matching soliton model scaling.

Different scaling behavior compared to the traditional large $N_c$ limit.

Abstract

In the large $N_c$ limit of QCD, baryons can be modeled as solitons, for instance, as Skyrmions. This modeling has been justified by Witten's demonstration that all properties of baryons and mesons scale with $N_c^{-1/2}$ in the same way as the analogous meson-based soliton model scales with a generic meson-meson coupling constant $g$. An alternative large $N_c$ limit (the orientifold large $N_c$ limit) has recently been proposed in which quarks transform in the two-index antisymmetric representation of $SU(N_c)$. By carrying out the analog of Witten's analysis for the new orientifold large $N_c$ limit, we show that baryons and solitons can also be identified in the orientifold large $N_c$ limit. However, in the orientifold large $N_c$ limit, the interaction amplitudes and matrix elements scale with $N_c^{-1}$ in the same way as soliton models scale with the generic meson coupling constant $g$ rather than as $N_c^{-1/2}$ as in the traditional large $N_c$ limit.