Isospin violation in J/Psi to phi pi0 eta decay and the f0-a0 mixing

Abstract

The isospin violating $J/\Psi\to \phi \pi^0 \eta$ decay is thought to be dominated by the mixing of the $f_0(980)$ and $a_0(980)$ scalar resonances. We make a theoretical evaluation of the $J/\Psi\to \phi \pi^0 \eta$ decay extending our own previous model for other $J/\Psi$ decays into one vector meson and two pseudoscalars using the techniques of the chiral unitary approach. The scalar resonances are dynamically generated through the final state interaction of the pseudoscalar mesons implementing unitarity from the lowest order ChPT amplitudes. Besides the direct $J/\Psi\phi PP$ vertex, other mechanisms like the sequential exchange of vector and axial-vector mesons are shown to be important in order to obtain the actual strength of the mixing. We get a very good agreement with the $\pi^0 \eta$ invariant mass distribution and branching ratio with recent BESIII data. Quantification of the $f_0(980)-a_0(980)$ mixing is done and compared with results from several experiments.