First observation of the decay ≡ c + →≡ 0 e + ν e and an estimate of the ≡ c + ≡ c 0 lifetime ratio

Using the CLEO II detector at the Cornell Electron Storage Ring we have observed the decay modes ≡ c + →≡ 0 e + ν e and ≡ c 0 → ≡ - e + V e by the detection of a ≡-positron pair of appropriate invariant mass. We find B(≡ c + →≡ 0 e + ν e )σ(e + e - →≡ c + X) = 1.55±0.33±0.25 pb, B(≡ c 0 →≡ - e + ν e )σ(e + e - →≡ c 0 X) = 0.63±0.12±0.10 pb, B(≡ c + →≡-π + π + )/B(≡ c + →≡ 0 e + ν e ) = 0.44±0.11 -0.06 +0.11 , and B(≡ c 0 →≡ - π + )/B(≡ c 0 →≡-e + ν e ) = 0.32±0.10 -0.03 +0.05 . Assuming the ≡ c + and ≡ c 0 are equally produced in e + e - annihilation events at 10 GeV, the lifetime ratio of ≡ c + /≡ c 0 is measured to be 2.46±0.70 -0.23 +0.33 .