Updated study of the ηc and η′c decays into light vector mesons

We re-investigate the exclusive decays of eta(c) and eta'(c) to a pair of light vector mesons, i.e. eta(c)(eta'(c)) -> V V. The long-distance intermediate meson loop (IML) effects are evaluated as a non-perturbative mechanism in addition to the short-distance c (c) over bar. annihilation contributions. We show that both processes can be reasonably well constrained with the help of the available experimental data. Since eta(c) and eta'(c) are the spin-0 partners of J/psi and psi', respectively, our study is useful for gaining insights into the pQCD helicity selection rule violations in charmonium decays and the long-standing rho pi puzzle. (c) 2012 Elsevier B.V. All rights reserved.