On sharp Strichartz estimate for hyperbolic Schrödinger equation on $\mathbb{T}^3$
Baoping Liu, Xu Zheng
TL;DR
This work establishes a sharp Strichartz estimate for the hyperbolic Schrödinger equation on the 3-torus, removing the $N^{\varepsilon}$ loss that appears in prior decoupling-based results. The authors reduce the endpoint to an $L^4_{t,x}$ bound and tackle it via incidence geometry, analyzing frequency parallelograms constrained by a cone and exploiting Szemerédi–Trotter type bounds. Building on this, they derive optimal local well-posedness results for nonlinear hyperbolic Schrödinger equations on $\mathbb T^3$ in the natural Sobolev scales, and demonstrate ill-posedness at the critical index for the cubic case. The approach blends harmonic analysis on compact manifolds with incidence-geometry techniques, offering precise frequency-localized control and potential applicability to related dispersive PDEs on tori.
Abstract
We prove the sharp Strichartz estimate for hyperbolic Schrödinger equation on $\mathbb{T}^3 $ via an incidence geometry approach. As application, we obtain optimal local well-posedness of nonlinear hyperbolic Schrödinger equations.
