Isospin Symmetry Breaking in ρ\toπγDecay

Abstract

In terms of effective field theory and mixed propagator approach, we show that there is a larger hidden effect of isospin breaking in $ρ^0\toπ^0γ$ decay due to an $ω$ exchange, $ρ^0\toω\toπ^0γ$. The branching ratio is predicted as $B(ρ^0\toπ^0γ)=(11.67\pm 2.0)\times 10^{-4}$, which is much larger than Partcile Data Group's datum $(6.8\pm 1.7)\times 10^{-4}$ and one of charged mode, $B(ρ^\pm\toπ^\pmγ)=(4.5\pm 0.5)\times 10^{-4}$.