Physics Opportunities at an Electron-Ion Collider XI

Extracting the Pion Off-Shell Electromagnetic Form Factors

Feb 25, 2025, 9:25 AM

25m

Graham Center 140 (Miami, Florida International University, Modesto Maidique Campus)

talk Plenary

Speaker

Joao Pacheco de Melo (Laboratório de Fisica Teórica e Computacional, LFTC, UCS)

Description

We investigate the off-shell pion electromagnetic
form factors using phenomenological relativistic
constituent quark models. These models, which treat the
pion as a composite of massive, structureless quarks,
employ the Mandelstam approach to calculate the
microscopic form factors. Each model is parameterized by
two scale parameters fitted to the pion decay constant and charge radius.

Experimental data from the exclusive Sullivan process,
 $^1$H$(e,e',\pi^+)n$, analyzed within the framework of pion pole dominance and under the condition of low off-shell virtuality, enabled  the comparison  between our previous model predictions and the extracted  off-shell pion form factors.  One of the two off-shell form factors, inaccessible through conventional elastic electron scattering experiments, is obtained from the
exclusive Sullivan process cross-section data 
via a relation derived from the Ward-Takahashi identity 
for the pion electromagnetic current.

References

1. Off-shell pion properties: Electromagnetic form factors and light-front wave functions.
   Jurandi Leão,J. P. B. C. de Melo,T. Frederico, Ho-Meoyng Choi and and Chueng-Ryong Ji.
   Phys. Rev. D110, 074035 (2024).

2. Pion off-shell electromagnetic form factors:
   Data extraction and model analysis.

Ho-Meoyng Choi,T. Frederico, Chueng-Ryong Ji, J. P. B. C. de Melo.

Phys. Rev. D100, 116020 (2019).