Results on weak decays of charmed mesons from E691

Using data from Fermilab experiment E691, results on Ds± decays into the final states π±π-π+, π±π-π+π0, and K+K-π±π0 are presented. For the π±π-π+ decay, the fractions due to ρ0π± and f0(975)π± have been found. A search for the ηπ± and ωπ± components in the mode π±π-π+π0 is performed. The Φπ±π0 and non-resonant component of the K+K-π±π0 is also studied. Results for the Cabibbo-suppressed D± decays into these modes are also presented. The final state D+ → K-π+e+νe is studied and the D+ → K*0e+νe branching ratio of (4.5 ± 0.7 ± 0.5)% is measured. The branching ratio to the non-resonant (K-π+)NRe+νe final state is found to be less than 0.7% at the 90% confidence level. The K*0 mesons have a ratio of longitudinal to transverse polarization of 2.4-0.9+1.7 ± 0.2