arXiv subjects

Marco Ghilardi

Publications and source records attributed to Marco Ghilardi.

3 recordsLinked to original sources

arXiv2026

Next-to-leading order FsQED corrections to radiative pion pair production

We compute the next-to-leading order corrections to the radiative return process $e^+ e^- \to \pi^+ \pi^- \gamma$ within the FsQED approach to embed the pion form factor in the calculation of loop integrals. We compare our results with those of the factorised scalar QED approach, as well as with previous predictions obtained by us in the generalised vector meson dominance model. We show the numerical impact of the structure-dependent corrections on various observables of interest for radiative return experiments at flavour factories. Following recent input from the literature, we include in our calculation also leading corrections beyond FsQED and we provide a first estimate of such contributions. We also investigate additional mechanisms contributing to final-state radiation at center-of-mass energies around the $\phi$-meson resonance, such as radiative $\phi$ decays, presenting numerical results that are relevant for the KLOE experiment. These novel features are implemented in the Monte Carlo event generator BabaYaga@NLO, which can now be used to evaluate the impact of the modelling of pion-photon interaction in radiative return measurements.

hep-ph↗

arXiv2026

Structure-dependent radiative corrections to $e^+ e^- \to \pi^+ \pi^- \gamma$ in the GVMD approach

We compute the radiative corrections to the process of two-pion production in association with a hard photon in $e^+ e^-$ annihilation by taking into account the non-perturbative structure of the pion in the one-loop calculation. For this purpose, we adopt the generalised vector meson dominance model to insert the pion form factor in loop integrals for the treatment of final-state radiation and initial-final state interference at next-to-leading order. We compare our predictions with the results of the naive factorised scalar QED approach for experimentally relevant observables in the measurement of the $e^+ e^- \to \pi^+ \pi^- \gamma$ process. The computation extends previous results obtained for the energy scan process $e^+ e^- \to \pi^+ \pi^-$ and can be used to quantify the uncertainty due to the model describing the pion-photon interaction in radiative return experiments at flavour factories.

hep-ph↗

arXiv2026

Radiative return at NLOPS accuracy

The radiative return, together with the energy scan, is the method used at flavour factories to measure the pion form factor, which is a crucial input for the data-driven dispersive computation of the leading-order hadronic contribution to the muon anomalous magnetic moment. We consider the radiative hadronic and leptonic channels of main experimental interest, namely the processes $e^+e^-\to X^+X^-\gamma$, with $X = \{\pi \, , \mu \}$. For such processes, we compute the exact next-to-leading order (NLO) corrections matched to a Parton Shower (PS) to describe exclusive multiple photon emission. All sources of radiative corrections from initial-state and final-state radiation, as well as their interference, are considered according to QED for $e^+e^-\to\mu^+\mu^-\gamma$ and QED$\oplus$F$\times$sQED (Factorised scalar QED) for $e^+e^-\to\pi^+\pi^-\gamma$. We describe in detail the novel features of our PS approach to compute the fixed-order corrections in association with higher-order contributions to $2\to3$ processes, with a hard photon in the final state. We present validation tests and comparisons with NLO predictions available in the literature to cross-check various ingredients of our formulation. We also show numerical results at NLOPS accuracy according to realistic event selection criteria for precision measurements at flavour factories. Our calculation is implemented in an updated version of the Monte Carlo event generator BabaYaga@NLO, which can be used for fully exclusive simulations and data analysis in radiative return experiments.

hep-ph↗