R\^ole of the pion electromagnetic form factor in the $\Delta(1232) \to \gamma^\ast N$ timelike transition

Understand

The $\Delta(1232) \to \gamma^\ast N$ magnetic dipole form factor ($G_M^\ast$) is described here within a new covariant model that combines the valence quark core together with the pion cloud contributions.

• The pion cloud term is parameterized by two terms: one connected to the pion electromagnetic form factor, the other to the photon interaction with intermediate baryon states.
• The model can be used in studies of pp and heavy ion collisions.
• In the timelike region this new model improves the results obtained with a constant form factor model fixed at its value at zero momentum transfer.