Well-posedness results for a generalized Klein-Gordon-Schr\"odinger system

We consider the Klein-Gordon-Schr"odinger system \begin{align*} i \partial_t \psi + \Delta \psi & = \phi^2 \psi - \phi \psi \ (\Box +1)\phi & = -2|\psi|^2 \phi + |\psi|^2 \end{align*} with additional cubic terms and Cauchy data $$\psi (0)={\psi }_0\in H^s({\mathbb{R}}^n),\varphi (0)={\varphi }_0\in H^k({\mathbb{R}}^n),({\mathrm{\partial }}_t\varphi )(0)={\varphi }_1\in H^{k-1}({\mathbb{R}}^n)$$ in space dimensions $n=2$ and $n=3$ . We prove local existence, uniqueness and continuous dependence on the data in Bourgain-Klainerman-Machedon spaces for low regularity data, e.g. for $s=-\frac{1}{8}$, $k=\frac{3}{8}+ϵ$ in the case $n=2$ and $s=0$ , $k=\frac{1}{2}+ϵ$ in the case $n=3$. Global well-posedness in energy space is also obtained as a special case. Moreover, we show “unconditional” uniqueness in the space $\psi \in C^0([0,T],H^s) , , , \phi \in C^0([0,T],H^{s+\frac{1}{2}}) \cap C^1([0,T],H^{s-\frac{1}{2}})$,if$s > \frac{3}{22}$for$n=2$and$s > \frac{1}{2}$for$n=3$.