Study of \eta-\eta' mixing from radiative decay processes
(Jan 10, 2012)Abstract
We perform a thorough analysis of the VP\gamma(\gamma*) and
P\gamma\gamma(\gamma*) decays in the resonance chiral theory, where V stand for
the vector resonances \rho, K*, ømega, \phi, P stand for \pi, K, \eta, \eta'
and \gamma* subsequently decays into lepton pairs. Upon imposing QCD
short-distance constraints on resonance couplings, the -> \pi
\gamma(\gamma*), -> \gamma(\gamma*), K^*0 -> K^0processes
only depend on one free parameter and -> \gamma(\gamma*) can be
completely predicted. The four mixing parameters of the \eta-\eta' system, i.e.
two mixing angles þeta8, þeta0 and two decay constants F8, F0, are
determined from radiative decays involving 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 -> e^+ e^-, \eta' -> e^+ e^- and -> \eta
\mu^+ \mu^-, which can be compared with the future measurement in these
channels.