Radiative decay width of theρ−meson

We present data on coherent ${\rho }^{-}$ production on nuclear targets and our application of the Primakoff formalism for extracting the radiative decay width for the transition ${\rho }^{-}\to {\pi }^{-}\gamma$. Assuming the presence of both electromagnetic and strong contributions to coherent production, we obtain $\Gamma ({\rho }^{-}\to {\pi }^{-}\gamma )=71\mathrm{}\pm 7$ keV, a result in good agreement with SU(3).