Endpoint Strichartz estimates with angular integrability and some applications

Abstract

The endpoint Strichartz estimate $\|e^{it\Delta} f\|_{L_t^2 L_x^\infty} \lesssim \|f\|_{L^2}$ is known to be false in two space dimensions. Taking averages spherically on the polar coordinates $x=\rho\omega$, $\rho>0$, $\omega\in\mathbb{S}^1$, Tao showed a substitute of the form $\|e^{it\Delta} f\|_{L_t^2L_\rho^\infty L_\omega^2} \lesssim \|f\|_{L^2}$. Here we address a weighted version of such spherically averaged estimates. As an application, the existence of solutions for the inhomogeneous nonlinear Schr\"odinger equation is shown for $L^2$ data.