Measurement of the branching fraction of D+ meson going to muon+ neutrino and the pseudoscalar decay constant fD+ using the full psi'' sample and search for neutral D meson going to proton-electron and neutral D meson going to antiproton-positron
Two analysis have been described in this work. In the first analysis, we measure the decay constant of the D + meson by measuring [Special characters omitted.] ( D + [arrow right] μ + ν) = (3.86±0.32±0.09)×10 -4 using 818 pb -1 of data taken on the ψ(3770) resonance with the CLEO detector at the CESR collider. This is the full sample of taken acquired by CLEO-c at this center-of-mass energy. Taken along with precision measurement of the lifetime, and assuming | V cs | = | V ud |, we derive f D + = (205.8 ± 8.5 ± 2.5) MeV. We also set a 90% confidence upper limit on [Special characters omitted.] ( D + [arrow right] e + ν) < 8.8 × 10 -6 . In the second analysis we search for simultaneous baryon and lepton number violating decays of the D 0 meson. Specifically, we use 281 pb -1 of data taken on the ψ(3770) resonance with CLEO-c detector to look for decays D 0 [arrow right] p¯e + , D¯ 0 [arrow right] p¯e + , D 0 [arrow right] pe - and D¯ 0 [arrow right] pe - . We find no significant signals and set the following branching fraction upper limits: D 0 [arrow right] p¯e + ( D¯ 0 [arrow right] p¯e + ) < 1.1 × 10 -5 and D 0 [arrow right] pe - ( D¯ 0 [arrow right] pe - ) < 1.0 × 10 -5 , both at 90% confidence level.