Search for the decay modes D0→e +e -, D0→μ +μ -, and D0→e ±μ∓

Abstract

We present searches for the rare decay modes D0→e +e -, D0→μ +μ -, and D0→e ±μ ∓ in continuum e +e -→cc̄ events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468fb -1. These decays are highly Glashow-Iliopoulos-Maiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D0→μ +μ - channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the Feldman-Cousins method, we set the following 90% confidence level intervals on the branching fractions: B(D0→e +e -)<1. 7×10 -7, B(D0→μ +μ -) within [0.6,8.1]×10 -7, and B(D0→e ±μ ∓)<3.3×10 -7. © 2012 American Physical Society.