The Uses of Chiral Anomaly for Determination of the Number of Colors

Abstract

The $N_c$-dependence of the vertices $PPP\gamma$, where $P$ is a pseudoscalar meson and $N_c$ is the number of colors, is analyzed with regard for the $N_c$-dependence of the quark charges. It is shown that the best processes for the determination of $N_c$ are the reactions $K\gamma \to K\pi$ and ${\pi }^{p}m\gamma \to {\pi }^{\pm }\eta$ as well as the decay $\eta \text{ra}{\pi }^{+}{\pi }^{-}\gamma$. The measurement of the cross section $\sigma ({\pi }^{-}\gamma \text{ra}{\pi }^{-}\eta )$ at the VES facility at the IHEP agrees with the value $N_c=3$.

Comments: 7 pages, 1 figure; accepted to Phys. Atom. Nucl., references added