Radiative decays, nonet symmetry, and SU(3) breaking

We reexamine the problem of simultaneously describing in a consistent way all radiative and leptonic decays of light mesons (V --> P gamma, P --> V gamma, P --> gamma gamma, V --> e(+)e(-)). For this purpose, we rely on the hidden local symmetry model in both its anomalous and non-anomalous sectors. We show that the SU(3) symmetry breaking scheme proposed by Bando, Kugo and Yamawaki, supplemented with nonet symmetry breaking in the pseudoscalar sector, allows one to reach a nice agreement with all data, except for the K*(+/-) radiative decay. An extension of this breaking pattern allows one to account for this particular decay mode too. Considered together, the whole set of radiative decays provides a pseudoscalar mixing angle theta(P) similar or equal to 11 degrees and a value for theta(V) which is similar or equal to 3 degrees from that of ideal mixing. We also show that it is impossible, in a practical sense, to disentangle the effects of nonet symmetry breaking and those of glue inside the eta', using only light meson decays. [S0556-2821(99)01013-9].