Global well-posedness for a L2L^2-critical nonlinear higher-order Schr\"odinger equation

We prove the global well-posedness for a $L^2$-critical defocusing cubic higher-order Schr\"odinger equation, namely $$i\partial_t u + \Lambda^k u = -|u|^2 u,$$ where $\Lambda=\sqrt{-\Delta}$ and $k\geq 3, k \in \mathbb{Z}$ in $\mathbb{R}^k$ with initial data $u_0 \in H^\gamma, \gamma>\gamma(k):=\frac{k(4k-1)}{14k-3}$.Comment: Revised Versio