Finite width effects in φ radiative decays

Abstract

We calculate the decay rates φ→γπ⁰π⁰ and γπ⁰η in very good agreement with the recent accurate experimental data. We also point out the necessity of a $\text{φγK}{}^0\text{K}{}^{\mathrm{<mspace\; xmlns="true"\; sp="0.2"\; width="2px"\; linebreak="nobreak"\; is="true"></mspace><mtext>0</mtext>}}$ contact vertex beyond the pure K⁺K⁻ loop model. The decay widths φ→γf₀(980) and φ→γa₀(980) are also calculated taking into account the finite widths of the scalar resonances f₀(980) and a₀(980). The latter are shown to be essential in order to obtain meaningful results. The resulting decay rates to γf₀(980) and γa₀(980) are in good agreement with the experimental ones without invoking isospin breaking in the couplings of the f₀(980) and a₀(980) resonances to the K⁺K⁻ and $\text{K}{}^0\text{K}{}^{\mathrm{<mspace\; xmlns="true"\; sp="0.2"\; width="2px"\; linebreak="nobreak"\; is="true"></mspace><mtext>0</mtext>}}$ channels, at odds with recent proposals. The derived formula for calculating these φ radiative decay widths can be also applied in their own experimental analyses in order to obtain more precise results.