Global well-posedness for Schrödinger equation with derivative in $H^{1/2}(\R)$

Changxing Miao, Yifei Wu, Guixiang Xu

Published 2009-12-23, updated 2010-08-03Version 2

In this paper, we consider the Cauchy problem of the cubic nonlinear Schr\"{o}dinger equation with derivative in $H^s(\R)$. This equation was known to be the local well-posedness for $s\geq \frac12$ (Takaoka,1999), ill-posedness for $s<\frac12$ (Biagioni and Linares, 2001, etc.) and global well-posedness for $s>\frac12$ (I-team, 2002). In this paper, we show that it is global well-posedness in $H^{1/2(\R)$. The main approach is the third generation I-method combined with some additional resonant decomposition technique. The resonant decomposition is applied to control the singularity coming from the resonant interaction.