Semiclassical resolvent bounds for short range $L^\infty$ potentials with singularities at the origin

Abstract: We consider, for $h, E > 0$, resolvent estimates for the semiclassical Schr\"odinger operator $-h^2 \Delta + V - E$. Near infinity, the potential takes the form $V = V_L+ V_S$, where $V_L$ is a long range potential which is Lipschitz with respect to the radial variable, while $V_S = O(|x|^{-1} (\log |x|)^{-\rho})$ for some $\rho > 1$. Near the origin, $|V|$ may behave like $|x|^{-\beta}$, provided $0 \le \beta < 2(\sqrt{3} -1)$. We find that, for any $\tilde{\rho} > 1$, there are $C, \, h_0 >0$ such that we have a resolvent bound of the form $\exp(Ch^{-2} (\log(h^{-1}))^{1 + \tilde{\rho}})$ for all $h \in (0, h_0]$. The $h$-dependence of the bound improves if $V_S$ decays at a faster rate toward infinity.