The Radiative Decay of Vector Mesons

Abstract

In this paper, radiative decays $ρ^0 \to π^+π^-γ, π^0π^0γ$ ,$ϕ\to K^+K^-γ, K^0 \bar{K^0}γ$ are studied systematically in the U(3)$_L\timesU(3)_R$ chiral theory of mesons. The theoretical differential spectrum with respect to photon energy and branch ratio for $ρ^0 \to π^+π^-γ$ agree well with the experimental data. Differential spectrums and branch ratios for $ρ^0 \to π^0π^0γ, ϕ\to K^+ K^-γ,ϕ\to K^0\bar{K^0}γ$ are predicted. The process $ϕ\to K^0 \bar{K^0} γ$ is relevant to precision measurment of CP-violation parameters in the kaon systerm at a $ϕ$-factory. We give a complete estimate of the branch ratio for this decay process by including scalar resonance $f_0, a_0$ poles, nonresonant smooth amplitude and an abnormal parity process with $K^*$ pole which hasn't been considered before. We conclude that processes with intermediate $K^*$ do not pose a potential background problem for $ϕ\to K^0\bar{K}^0$ CP violation experiments.