- #1

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$$V_{1234}=\int_{x=0}^{\infty}\int_{y=0}^{\infty}d^3\pmb{x}d^3\pmb{y}\, j_{l_1}^*(a_1\pmb{x})j_{l_2}(a_2\pmb{x})|\pmb{x}-\pmb{y}|^{-1}j_{l_3}^*(a_3\pmb{y})j_{l_4}(a_4\pmb{y})$$

where $j_l(r)$ are spherical Bessel functions. Does anyone know how to solve these integrals analytically?