Meson exchange currents in pion double charge exchange reaction

It is shown that in the Born approximation the forward scattering pion double charge exchange (DCX) amplitude for the meson exchange current (MEC) mechanism does not depend on the energy. The unitarization of the amplidute as well as the contributions of the ρ, σ, and f0 mesons into MEC mechanism based on the composite meson model increase the cross section and lead to its energy dependence.