Studies of the Cabbibo-Suppressed Decays $D^{+}\to {\pi }^0{\ell }^{+}\nu$ and $D^{+}\to \eta e^{+}{\nu }_e$

Abstract

Using 4.8 fb${}^{-1}$ of data taken with the CLEO II detector, the branching fraction for the Cabibbo-suppressed decay $D^{+}\to {\pi }^0{\ell }^{+}\nu$ measured relative to the Cabibbo favored decay $D^{+}\to \overline{K^0}{\ell }^{+}\nu$ is found to be $0.046\pm 0.014\pm 0.017$. Using $V_{cs}$ and $V_{cd}$ from unitarity constraints, we determine $|f_{+}^{\pi }(0)/f_{+}^K(0){|}^2=0.9\pm 0.3\pm 0.3$ We also present a 90% confidence level upper limit for the branching ratio of the decay $D^{+}\to \eta e^{+}{\nu }_e$ relative to that for $D^{+}\to {\pi }^0{e}^{+}{\nu }_e$ of 1.5.

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