Pion electromagnetic form factor in the instanton vacuum

We have calculated the three-point correlation function for the electromagnetic interaction of the pion in an ensemble of instantons and anti-instantons, modeling the QCD vacuum. The results are well described by a pion pole, and the pion form factor is extracted, nicely following a standard monopole fit. The experimental data on the form factor are well reproduced, provided an average instanton size is fixed at $\overline{\rho }=0.35\mathrm{}\pm 0.03$ fm, the same as found for a variety of other correlation functions and was found on the lattice.