Radiative decay of rho^0 and phi mesons in a chiral unitary approach

TL;DR

This paper investigates the radiative decays of rho^0 and phi mesons using a chiral unitary approach, revealing how final state interactions influence decay spectra and resonance appearances, with results aligning with recent experimental data.

Contribution

It introduces a chiral unitary framework to analyze meson decays, highlighting the role of final state interactions and resonance structures in decay spectra.

Findings

Final state interactions moderately affect rho^0 decay photon spectrum.

Phi decay spectra show clear f_0(980) resonance peak.

Predicted branching ratios agree with recent experimental measurements.

Abstract

We study the rho^0 and phi decays into pi^+ pi^- gamma, pi^0 pi^0 gamma and phi into pi^0 eta gamma using a chiral unitary approach to deal with the final state interaction of the M M system. The final state interaction modifies only moderately the large momenta tail of the photon spectrum of the rho^0 --> pi^+ pi^- gamma decay. In the case of phi decay the contribution to pi^+ pi^- gamma and pi^0 pi^0 gamma decay proceeds via kaonic loops and gives a distribution of pi pi invariant masses in which the f_0(980) resonance shows up with a very distinct peak. The spectrum found for phi --> pi^0 pi^0 gamma decay agrees with the recent experimental results obtained at Novosibirsk. The branching ratio for phi --> pi^0 eta gamma, dominated by the a_0(980), is also in agreement with recent Novosibirsk results.