An Isobar Model of e+ e- --> pi+ pi- pi0 pi0

In this paper, several calculations of the matrix elements for processes that may contribute to e+ e- --> pi+ pi- pi0 pi0 using the isobar model and the Lorentz invariant amplitude method are presented. The formulas may be used to determine the electromagnetic form factors of the rho meson if e+ e- --> rho+ rho- contributes to e+ e- --> pi+ pi- pi0 pi0 The electromagnetic form factors of the rho meson are predicted by QCD calculations. The formulas in this paper may be used to study the a_1 meson if e^+ e^- --> a_1 \pi contributes to e+ e- --> pi+ pi- pi0 pi0.