$L^1\rightarrow L^\infty$ Dispersive estimates for Coulomb waves

Adam Black, Ebru Toprak, Bruno Vergara Biggio, Jiahua Zou

Published 2023-09-04Version 1

We show the time decay of spherically symmetric Coulomb waves in $\R^{3}$ for the case of a repulsive charge. By means of a distorted Fourier transform adapted to $H=-\Delta+q\cdot |x|^{-1}$, with $q>0$, we explicitly compute the kernel of the evolution operator $e^{itH}$. A detailed analysis of the kernel is then used to prove that for large times, $e^{i t H}$ obeys an $L^1 \to L^\infty$ dispersive estimate with the natural decay rate $t^{-\f32}$.