Optimal bounds for embedded eigenvalues of one-dimensional discrete Schrödinger operators with decaying potentials

In this paper, we consider one-dimensional discrete Schrödinger operators \begin{align} Hu(n)=(Δ+V)u(n)\nonumber \end{align} on $\ell^2(\mathbb{N})$ with a self-adjoint boundary condition at $n=0$, where $Δ$ denotes the discrete Laplacian and $V(n)$ is a real-valued perturbation satisfying $$V