CP-odd A^0 production at e^+e^- colliders in MSSM with CP violating phases

We study the production of a heavy CP-odd $A^0$ boson in association with a photon $e^{+}{e}^{-}\to A^0\gamma$ and a Z boson $e^{+}{e}^{-}\to A^{0}Z$ as well as the single production of $A^0$ via $e^{+}{e}^{-}\to {\nu }_e{\bar{\nu }}_e{A}^0$ in the MSSM with CP violating phases. In the case of $e^{+}{e}^{-}\to A^0\gamma \mathrm{/}{A}^{0}Z$, we show that the squark contribution, which vanishes in the MSSM with real parameters, turns out to be sizeable in presence of CP violating phases in the soft SUSY parameters. For $e^{+}{e}^{-}\to {\nu }_e{\bar{\nu }}_e{A}^0$ in both the 2HDM and MSSM with real parameters, the cross section does not reach observable rates at a NLC. It is found that with a large CP violating phase for $A_t$, cross sections of the order 0.1 fb are attainable for all the processes $e^{+}{e}^{-}\to A^0\gamma$, $e^{+}{e}^{-}\to A^{0}Z$ and $e^{+}{e}^{-}\to {\nu }_e{\bar{\nu }}_e{A}^0$.