Researchers have computed next-to-leading order (NLO) corrections for the radiative return process $e^+ e^- \to \pi^+ \pi^- \gamma$. This calculation was performed within the framework of Final-State Scalar Quantum Electrodynamics (FsQED), which allows for the embedding of the pion form factor in the computation of loop integrals. The work compares these results with previous approximations, such as the factorised scalar QED approach and predictions obtained using the generalised vector meson dominance model.

This study evaluates the numerical impact of structure-dependent corrections on various observables relevant for radiative return experiments at flavour factories. Furthermore, leading corrections beyond the FsQED model have been included, providing a first estimate of these contributions. Additional mechanisms contributing to final-state radiation at center-of-mass energies around the $\phi$-meson resonance, such as radiative $\phi$ decays, were also investigated, presenting numerical results relevant for the KLOE experiment.

These novel features have been implemented in the BabaYaga@NLO Monte Carlo event generator. This update will allow for a more precise evaluation of the impact of pion-photon interaction modeling in radiative return measurements. The inclusion of higher-order corrections and the consideration of other radiation mechanisms are crucial for refining the accuracy of theoretical predictions and their comparison with experimental data in particle physics.