by Guest » Fri Jan 15, 2021 8:31 am
[tex]\int\limits_{0}^{\infty} e^{i\vec{k}(\vec{y}-\vec{x})}\vec{k}^{-2}d^3k[/tex] = [tex]\int\limits_{0}^{2\pi} d\varphi\int\limits_{-1}^{1} d cos\lambda \int\limits_{0}^{\infty} d|\vec{k}|e^{i cos\lambda|\vec{k}||\vec{x}-\vec{y}|}[/tex]