Studies of the Cabibbo-suppressed decays D+ → π0ℓ+v and D+ → ηe+ve

Abstract Using 4.8 fb −1 of data taken with the CLEO II detector, the branching fraction for the Cabibbo suppressed decay D + → π 0 l + ν measured relative to the Cabibbo favored decay D + → K 0 l + ν is found to be 0.046 ± 0.014 ± 0.017. Using V cs and V cd from unitarity constraints, we determine | ƒ + π (0) ƒ + K (0) | 2 = 0.9 ± 0.3 ± 0.3 We also present a 90% confidence level upper limit for the branching ratio of the decay D + → ηe + ν e relative to that for D + → π 0 e + ν e of 1.5.