Further regularity results for almost cubic nonlinear Schrodinger equation

We present three results related with the regularity of solutions of the almost cubic NLS. in the first one, following Ozawa's idea, we establish mass and energy conservation for the solutions without regularizing the initial datum. Our second result is the H(s) well-posedness for the Cauchy problem for 0 < s < 1. Finally, we show that the same solutions are also in some Bourgain spaces for possibly a smaller time interval. In all of our results, the non-local nonlinear term in the equation is shown to act like a cubic nonlinearity on the appropriate Sobolev and Besov spaces. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.