Pion off-shell form factors

by Prof. J. Pacheco B. C. de Melo (Laboratório de Física Teórica e Computacional - LFTC - UCS/UNICID)

Monday Jan 26, 2026, 2:00 PM → 4:00 PM Asia/Shanghai

C1204 (Physical Science Bldg, USTC)

Abstract:

We investigate 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 microscopic form factors. Each model is parameterized by two values, constrained by precise reproduction of the pion decay constant and charge radius. Data from the Sullivan process, $^1$H$(e,e',\pi^+)n$, analyzed within the framework of pion pole dominance and under conditions of low off-shell virtuality, enables both comparison with our model predictions and extraction of the off-shell pion form factor. This form factor, inaccessible through conventional electron scattering experiments, is obtained via a relation derived from the Ward-Takahashi identity for the pion electromagnetic current.

About the speaker:

João Pacheco B. C. de Melo is a professor and coordinator of the Theoretical and Computational Physics Laboratory at Cruzeiro do Sul University in Brazil. He received his Ph.D. from the University of São Paulo in 1998 and conducted postdoctoral research at Pierre and Marie Curie University and São Paulo State University. His research centers on hadronic physics, non-perturbative quantum field theory, and light-front formalism, with particular expertise in applying light-front method to study hadron properties. He has published around 100 papers in this area. In 2026, he was award the Chinese Academy of Sciences President's International Fellowship Initiative (PIFI).

---

Date and Time：Jan. 26 (Monday) 14:00 - 15:30 (BJT)
Location：C1204, Physical Sciences Bldg., USTC
Zoom meeting ID: 921 0170 7592
Passcode: 862496 

Zoom link: https://zoom.us/j/92101707592?pwd=H3bqGkCpzkDenx2QbKs286YmFCc1L5.1