Global low-regularity solutions for Kadomtsev-Petviashvili equation

We study the initial value problem for the KP-II equation. We prove the existence of solutions to the integral equation corresponding to KP-II for any data in $L^2$, removing the additional condition imposed in [15]. Following a method recently developed by J. Bourgain we obtain global solutions to KP-II with data below $L^2$.