$L^p$-continuity of wave operators for higher order Schrödinger operators with threshold eigenvalues in high dimensions
M. Burak Erdogan, William R. Green, Kevin LaMaster
TL;DR
This work establishes $L^p$-boundedness of wave operators for higher-order Schrödinger operators $H=(- abla^2)^m+V$ in dimensions $n>4m$ when zero is an eigenvalue but there are no threshold resonances or positive eigenvalues. The authors develop a unified low-energy analysis using the stationary representation of $W_+$, the symmetric resolvent identity, and Jensen–Nenciu inversion to control the zero-energy singularity, extending and simplifying the classical $m=1$ theory. Under decay and spectral assumptions on $V$, they prove that the low-energy piece $W_{low,k}$ is bounded on $L^p(R^n)$ for all $1\le p<rac{n}{2m}$ (for sufficiently large $k$), enabling dispersive-type estimates via the intertwining identity. Overall, the paper provides a parity-agnostic, streamlined framework for $L^p$-continuity of wave operators in high dimensions with threshold eigenvalues, generalizing prior results and offering a robust tool for future dispersive analyses of higher-order operators.
Abstract
We consider the higher order Schrödinger operator $H=(-Δ)^m+V(x)$ in $n$ dimensions with real-valued potential $V$ when $n>4m$, $m\in \mathbb N$. We adapt our recent results for $m>1$ to show that when $H$ has a threshold eigenvalue the wave operators are bounded on $L^p(\mathbb R^n)$ for the natural range $1\leq p<\frac{n}{2m}$ in both even and odd dimensions. The approach used works without distinguishing even and odd cases, and matches the range of boundedness in the classical case when $m=1$. The proof applies in the classical $m=1$ case as well and simplifies the argument.
