Baryons from Quarks in the $1/N$ Expansion

Journal article

We present a diagrammatic analysis of baryons in the $1/N$ expansion, where $N$ is the number of QCD colors. We use this method to show that there are an infinite number of degenerate baryon states in the large-$N$ limit. We also show that forward matrix elements of quark bilinear operators satisfy the static quark-model relations in this limit, and enumerate the corrections to these relations to all orders in $1/N$. These results hold for any number of light quark flavors, and the methods used can be extended to arbitrary operators. Our results imply that for two flavors, the quark-model relations for the axial currents and magnetic moments get corrections of order $1/N^2$. For three or more flavors, the results are more complicated, and corrections are generically of order $1/N$. We write an explicit effective lagrangian which can be used to carry out chiral perturbation theory calculations in the $1/N$ expansion. Finally, we compare our results to what is expected from a chiral constituent quark model.

Authors: Luty, M; March-Russell, J

• Journal: Nucl.Phys. B
• Volume: 426
• Issue: 1
• Pages: 71-93
• Publication date: 1993-10-28
• DOI: 10.1016/0550-3213(94)90126-0
• ISSN: 0550-3213
• Language: English
• Keywords: nucl-th; hep-ph