Finite width effects in φ radiative decays

Abstract

We calculate the decay rates φ→ γπ 0 π 0 and γπ 0 η in very good agreement with the recent accurate experimental data. We also point out the necessity of a φγK 0 K 0 contact vertex beyond the pure K + K − loop model. The decay widths φ→ γf 0(980) and φ→ γa 0(980) are also calculated taking into account the finite widths of the scalar resonances f 0(980) and a 0(980). The latter are shown to be essential in order to obtain meaningful results. The resulting decay rates to γf 0(980) and γa 0(980) are in good agreement with the experimental ones without invoking isospin breaking in the couplings of the f 0(980) and a 0(980) resonances to the K + K − and K 0 K 0 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.