Speaker
Description
The off-shell pion electromagnetic form factors are explored
using phenomenological relativistic constituent quark models. These composite pion models feature
massive, structureless blue quark and antiquark, allowing the computation of microscopic form factors
via the Mandelstam approach. Each model relies on two parameters which are determined by closely reproducing the pion decay constant and charge radius.
The existing data on the cross-sections for the Sullivan process, $^1\text{H}(e,e',\pi^+)n$, where pion pole dominance and low off-shell virtuality permit comparison with the model results as well as
the extraction of the off-shell pion form factor.
The off-shell form factor is not directly accessible by electron scattering but can be derived from a relation
based on the Ward-Takahashi identity for the pion electromagnetic current.
We found that the adopted models reproduce the extracted off-shell form factor
$F_1(Q^2,t)$ for $t<0$ from these cross-sections with an accuracy of a few percent.
Additionally, we extracted the new form factor $g(Q^2,t)$
which is directly related with the charge radius of the
pion $g(Q^2=0, m_\pi^2) =
within the models used in this work.
We also identify the pion valence parton distribution function (PDF)
and transverse momentum distribution (TMD) in terms of the light-front wave function and discuss their
on-shell properties.
