e+e−pairs fromπ−Areactions reexamined

We calculate dilepton production for the reactions ${\pi }^{-}\mathrm{C}$ and ${\pi }^{-}\mathrm{Pb}$ at 1.3 GeV within a semiclassical BUU transport model and compare our results to a previously published calculation. We show that a modified treatment of the $\rho$ meson production and propagation gives substantially different results. We, furthermore, discuss uncertainties related to the electromagnetic decay of the $\rho$ meson and the elementary ${\pi }^{-}\overrightarrow{N}{e}^{+}{e}^{-}X$ channels.