Analysis of nature of φ → γπη and φ → γπ0π0 decays

Abstract

We study interference patterns in the phi -> gamma a0 + pi0 rho -> gamma pi eta and phi -> gamma f0 + pi0 rho -> gamma pi0 pi0 reactions. Taking into account the interference, we fit the experimental data and show that the background reaction does not distort the pi0eta spectrum in the decay phi -> gamma pi eta everywhere over the energy region and does not distort the pi0 pi0 spectrum in the decay phi -> gamma pi0 pi0 when the invariant mass m_{pi0 pi0} > 670 MeV. We discuss the details of the scalar meson production in the radiative decays and note that there are conclusive arguments in favor of the one-loop mechanism phi -> K+K- -> gamma a0 (or gamma f0). We discuss also distinctions between the four-quark, molecular, and two-quark models and argue that the establishment of the scalar meson production mechanism in the phi radiative decays gives new strong evidence in favor of the four-quark nature of the scalar a0(980) and f0(980) mesons.