Observation of D0 Meson Decays to π+π-μ+μ- and K+K-μ+μ- Final States

The first observation of the D0→π+π-μ+μ- and D0→K+K-μ+μ- decays is reported using a sample of proton-proton collisions collected by LHCb at a center-of-mass energy of 8 TeV, and corresponding to 2 fb-1 of integrated luminosity. The corresponding branching fractions are measured using as normalization the decay D0→K-π+[μ+μ-]ρ0/ω, where the two muons are consistent with coming from the decay of a ρ0 or ω meson. The results are B(D0→π+π-μ+μ-)=(9.64±0.48±0.51±0.97)×10-7 and B(D0→K+K-μ+μ-)=(1.54±0.27±0.09±0.16)×10-7, where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalization branching fraction. The dependence of the branching fraction on the dimuon mass is also investigated.