Endpoint Mapping Properties of Wave Operators for Schrödinger Operators in Dimensions $n\ge3$

We study endpoint mapping properties of low-energy wave operators for Schrödinger operators $H=-Δ+V$ on $\mathbb R^n$, $n\ge3$. In dimension four, we prove that a zero-energy resonance prevents $L^1$ boundedness, whether or not zero is also an eigenvalue, under $|V(x)|\lesssim\langle x\rangle^{-β}$