MESON RADIATIVE DECAYS AND ANOMALY PHYSICS, A TEST OF QCD

We discuss in a wider context the connection of the results previously obtained on the decay processes eta/eta' --> pi(+)pi(-)gamma with res pect to the xi test of QCD proposed by Chanowitz. We show that one can add consistently to the four Chanowitz equations an equation obtained by Novikov et al. Akhoury and Frere which involves J/psi decays. We s how that the formerly defined model M(2) of the rho mass distribution accommodates easily this new constraint, while model M(1) indicates an inconsistency with eta data. We study the consequences of both M(1) a nd Mt in the description of eta/eta' --> mu(+)mu(-)gamma and eta/eta' --> e(+)e(-)gamma decays and we find a good agrement with the existing measurements. Consistency of the procedure we propose is illustrated by deriving from eta/eta' --> pi(+)pi(-)gamma and eta/eta' --> mu(+)mu (-)gamma decays the branching fractions eta/eta' --> gamma gamma. We f inally examine the consistency of the results obtained using the equat ions on box and triangle anomalies with the decays V --> P gamma and P --> V gamma, where P and V are the usual pseudoscalar and vector meso ns. Using standard SU(3) relations among coupling constants, we find c onsistency of our previous results with most of these radiative decay modes. The set of meson radiative decays thus addressed consists of 21 processes. As a result of all these checks, we improve the picture pr ovided by these two models, one (M(1)) in agreement with QCD, one (M(2 )) in basic disagreement with it. Ways to go beyond this confirmed amb iguity are proposed.