The $(n-1)$-linear restriction estimate in ${\mathbb{R}}^n$ with degenerate curvature

Abstract

We revisit the $(n-1)$-linear restriction estimate in ${\mathbb{R}}^n$ proved by the first author in \cite{Be-6} and refine the result in the case when the curvature assumptions contain small parameters. The standard $L^p$ estimate is replaced by a more complex norm/quasi-norm of type ${\ell }^p{L}^{\frac{2}{n-2}}$ which reflects the geometry of wave packet propagation and the degenerate curvature assumptions. The primary motivation for this work stems from a concrete application to the study of the quadratic nonlinear Schrödinger equation in ${\mathbb{R}}^{3+1}$, which is done in a companion paper \cite{BeBoCh}.

33 pages, comments welcome