Strichartz estimates for the Schr\"odinger equation on products of odd-dimensional spheres

Abstract

We prove Strichartz estimates for the Schr\"odinger equation which are scale-invariant up to an $\varepsilon$-loss on products of odd-dimensional spheres. Namely, for any product of odd-dimensional spheres $M=\mathbb{S}^{d_1}\times\cdots\times\mathbb{S}^{d_r}$ (so that $M$ is of dimension $d=d_1+\cdots+d_r$ and rank $r$) equipped with rational metrics, the following Strichartz estimate \begin{equation*} \|e^{it\Delta}f\|_{L^p(I\times M)}\leq C_\varepsilon\|f\|_{H^{\frac{d}{2}-\frac{d+2}{p}+\varepsilon}(M)} \end{equation*} holds for any $p\geq 2+\frac{8(s-1)}{sr}$, where $$s=\max\left\{\frac{2d_i}{d_i-1}, i=1,\ldots,r\right\}.$$