The $L^p$-boundedness of wave operators for nonhomogeneous fourth-order Schr\"odinger operators in high dimensions

This paper investigates the $L^p$-boundedness of wave operators associated with the nonhomogeneous fourth-order Sch\"odinger operator $H = \Delta^2 - \Delta + V(x)$ on $\mathbb{R}^n$. Assuming the real-valued potential $ V $ exhibits sufficient decay and regularity, we prove that for all dimensions $ n \geq 5 $, the wave operators $ W_{\pm}(H, H_0)$ are bounded on $L^{p}(\mathbb{R}^{n}) $ for all $ 1 \leq p \leq \infty $, provided that zero is a regular threshold of $H $. As applications, we derive the sharp $L^p$-$L^{p'}$ dispersive estimates for Schr\"odinger group $e^{-itH}$, as well as for the solutions operators $\cos(t \sqrt{H})$ and $\frac{\sin (t \sqrt{H})}{ \sqrt{H}}$ associated with the following beam equations with potentials: $$ \partial_t^2 u + \left(\Delta^2 -\Delta+ V(x) \right) u = 0, \ u(0, x) = f(x), \quad \partial_t u(0, x) = g(x),\ \ (t, x) \in \mathbb{R} \times \mathbb{R}^n,\ n\geq5, $$ where $p'$ denotes the H\"older conjugate of $p$, with $1 \leq p \leq 2$. Moreover, we remark that the same results hold for the operator $ \epsilon \Delta^2 - \Delta + V$ with a parameter $\epsilon>0,$ providing greater flexibility for the analysis of related equations.