Study of the ρ0 Decay into π0π0γ Within Framework of Chiral Perturbation Theory with Resonances

In this work, we calculate the Branching Ratio (BR) of the process ρ0→π0π0γ at tree level within the theoretical framework of with resonances, including the odd intrinsic parity sector. Owing to the nature of an effective field theory, the BR depends on three unknown couplings of the model: d4 and the combination c57=c5+c7. To constrain these unknown couplings, we use the experimental BR of this decay and explore the possibility of reducing the number of unknown couplings through the on-shell condition at one vertex. Our result suggests that off-shell conditions must be applied to both vertices, leading to a space parameter for the pair (c57,d4).