Supersymmetric Box Contributions to e^+ e^- to Z⁰ h⁰ and e^+ e^- to A⁰ h⁰

Within the MSSM we calculate the electroweak 1-loop box contributions to the processes $ e^+ e^- \rightarrow Z^0 h^0 $ and $ e^+ e^- \rightarrow A^0 h^0 $. We present detailed results for c. m. energies $\sqrt{s}=200$ GeV and $\sqrt{s}=500$ GeV as well as for $\tan\beta=2$ and $\tan\beta=50$. The box contributions to the process $ e^+ e^- \rightarrow Z^0 h^0 $ are, depending on $\sqrt{s}$ and $\tan\beta$, of the order -2 to -20\% and to $ e^+ e^- \rightarrow A^0 h^0 $ of 2 to 10\%.