The electromagnetic form factor of the charged pion encodes relevant information in hadron dynamics. On the one hand, its phase is related (modulo isospin-breaking corrections that will be carefully discussed) to the universal P-wave phase shift, that appears in a variety of hadronic processes. On the other hand, it appears as an essential input to describe hadronic electromagnetic interactions when employing dispersive formalisms. Furthermore, it is relevant to extract information about vector meson resonances.
In this talk, we employ a dispersion relation for the modulus of the form factor that allows to reconstruct its phase from its modulus above the unitarity cut. The latter has been extensively measured to high precision at colliders in the region ranging from threshold up to 3 GeV.
The formalism allows a data-based approach to extract the phase from threshold up to 2.5 GeV, well beyond the inelastic threshold where standard dispersive approaches cannot be applied.
With that information at hand different applications will be pursued, such as the value in the spacelike region, the transverse charge distribution of the pion or the impact of pQCD asymptotics.
References:
[1] E. Arriola and P. Sanchez-Puertas, "Phase of the electromagnetic form factor of the pion", Phys.Rev.D 110 (2024) 5, 054003, 2403.07121 [hep-ph]
[2] (to be covered partially) E. Arriola, W, Broniowski and P. Sanchez-Puertas, "Baryonic content of the pion", Phys.Lett.B 822 (2021) 136680, 2103.09131 [hep-ph]
Luiz Vale Silva