Supersymmetric enhancement of associated ZA⁰ production at e^+e^- colliders

We study the associated production of the A^0 neutral CP-odd Higgs boson with a neutral gauge boson Z in high energy e^+ e^- collisions at the one loop level. We present a detailed discussion for the total cross-section predicted in the context of the Minimal Supersymmetric Standard Model (MSSM) and make a comparison with the non-SUSY Two Higgs Doublet Model (THDM). We show that the MSSM cross-section may be enhanced compared to that for the THDM.