Quark-photon vertex and the pion charge radius - art. no. 045202

The rainbow truncation of the quark Dyson-Schwinger equation is combined wi th the ladder Bethe-Salpeter equation for the dressed quark-photon vertex: to study the low-momentum behavior of the pion electromagnetic form factor. With model gluon parameters previously fixed by the pion mass and decay co nstant, the pion charge radius r(pi) is found to be in good agreement with the data. In this work, about half of r(pi)(2) is seen to be attributable t o the presence of the rho pole in the solution of the ladder Bethe-Salpeter equation.