Searching for new physics in D0 → μ+μ-, e+e-, μ±e∓ at BES and/or the super charm-tau factory

In contrast with B-0-(B) over bar (0), B-s-(B) over bar (s) mixing where the standard model (SM) contributions overwhelm that of the new physics beyond standard model (BSM), a measured relatively large D-0-(D) over bar (0) mixing where the SM contribution is negligible, definitely implies the existence of the new physics BSM. It is natural to consider that the rare decays of D meson might be more sensitive to new phYsics, and the decay mode D-0 ->mu(+)mu(-) could be an ideal area to search for new physics because it is a flavor changing process. In this work we look for a trace of the new physics BSM in the leptonic decays of D-0. Concretely we discuss the contributions of unparticle or an extra gauge boson Z' while imposing the constraints set by fitting the D-0-(D) over bar (0) mixing data. We find that the long-distance SM effects for D-0-ll still exceed those contributions of the BSM under consideration, but for a double-flavor changing process such as D-0 ->mu(+/-)e(-/+), the new physics contribution would be significant.