Relating D0-D0 mixing and D0→l+l- with new physics

We point out how, in certain models of new physics, the same combination of couplings occurs in the amplitudes for both D-0-D-0 mixing and the rare decays D-0 -> l(+)l(-). If the new physics dominates and is responsible for the observed mixing, then a very simple correlation exists between the magnitudes of each; in fact the rates for the decay D-0 -> l(+)l(-) are completely fixed by the mixing. Observation of D-0 -> l(+)l(-) in excess of the standard model prediction could identify new physics contributions to D-0-D-0 mixing.