Search for the Flavor-Changing Neutral Current Decay $D^0\to {\mu }^{+}{\mu }^{-}$ with the HERA-B Detector

Abstract

We report on a search for the flavor-changing neutral current decay $D^0\to {\mu }^{+}{\mu }^{-}$ using $50\times 10^6$ events recorded with a dimuon trigger in interactions of 920 GeV protons with nuclei by the HERA-B experiment. We find no evidence for such decays and set a 90% confidence level upper limit on the branching fraction $Br(D^0\to {\mu }^{+}{\mu }^{-})<2.0\times 10^{-6}$.

17 pages, 4 figures (of which 1 double), paper to be submitted to Physics Letters B