$5p{}^2{P}_j\to 5d{}^2{D}_{3/2}$ transition matrix elements in atomic ${}^{87}\mathrm{Rb}$

A combined precision experimental and theoretical study of $5p{}^2{P}_j\to 5d{}^2{D}_{3/2}$ electric-dipole transition matrix elements in atomic ${}^{87}\mathrm{Rb}$ has shown that they are dominated by electron correlation. The relative size and sign of the measured matrix element ratio is found to be 1.068(8), in very good agreement with the value of 1.135 obtained from relativistic third-order many-body perturbation theory.