Study of η-η′ mixing from radiative decay processes

We perform a thorough analysis of the VP gamma(gamma*) and P gamma gamma(gamma*) decays in the resonance chiral theory, where V stands for the vector resonances rho, K*, omega, and phi; P stands for pi, K, eta, and eta'; and gamma* subsequently decays into lepton pairs. Upon imposing QCD short-distance constraints on resonance couplings, the omega -> pi gamma(gamma*), rho -> pi gamma(gamma*), K-*0 -> K-0 gamma processes only depend on one free parameter and pi -> gamma gamma(gamma*) can be completely predicted. The four mixing parameters of the eta-eta' system, i.e. two mixing angles theta(8), theta(0) and two decay constants F-8, F-0, are determined from radiative decays involving eta or eta'. The higher order low energy constants of the pseudo-Goldstone Lagrangian in the chiral anomaly sector are predicted by integrating out heavy resonances. We also predict the decay widths of rho -> pi e(+) e(-), eta' -> gamma e(+) e(-) and phi -> eta mu(+) mu(-), which can be compared with the future measurement in these channels.