Some addition theorems for spin-weighted spherical harmonics
arXiv:2410.23201
Abstract
We present some addition theorems for spin-weighted spherical harmonics, generalizing previous results for scalar (spin-zero) spherical harmonics. These addition theorems involve sums over the azimuthal quantum number of products of two spin-weighted spherical harmonics at different points on the two-sphere, either (or both) of which are differentiated with respect to one of their arguments.
12 pages, added discussion of physical applications, other minor changes, version accepted for publication