Large N_c

TL;DR

The paper discusses the application of the 1/N_c expansion in QCD to baryon phenomenology, highlighting its success in predicting baryon masses and aiding in the discovery of new heavy-quark baryons, with recent experimental validation.

Contribution

It emphasizes the role of the 1/N_c expansion in understanding baryon masses and spin-flavor symmetry, including recent experimental tests and predictions for undiscovered baryons.

Findings

Successful prediction of heavy-quark baryon masses.

Recent \\Omega_b^- mass measurement aligns with 1/N_c predictions.

Experimental data supports the 1/N_c expansion framework.

Abstract

The 1/N_c expansion of QCD with N_c=3 has been successful in explaining a wide variety of QCD phenomenology. Here I focus on the contracted spin-flavor symmetry of baryons in the large-N_c limit and deviations from spin-flavor symmetry due to corrections suppressed by powers of 1/N_c. Baryon masses provide an important example of the 1/N_c expansion, and successful predictions of masses of heavy-quark baryons continue to be tested by experiment. The ground state charmed baryon masses have all been measured, and five of the eight ground state bottom baryon masses have been found. Results of the 1/N_c expansion can aid in the discovery of the remaining bottom baryons. The brand new measurement of the \Omega_b^- mass by the CDF collaboration conflicts with the original D0 discovery value and is in excellent agreement with the prediction of the 1/N_c expansion.