Box Anomaly and ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}\gamma$ Decay

Abstract

In the framework of the "current scheme" of $\eta -{\eta }^{\prime }$ mixing we calculate the amplitude of the decay ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}\gamma$ in the soft limit and compare our results with recently reported values of the phenomenological additive terms to the $\rho$--meson background.

Comments: 7 pages, plain LaTeX, no figures