Study of Semileptonic Charm Decays Using the CLEOIII Detector

We investigate the decays D0→π−ℓ+ν and D0→K−ℓ+ν, where ℓ is e or μ, using approximately 7 fb−1 of data collected with the CLEO III detector. We find R0=B(D0→π−e+ν)/B(D0→K−e+ν)=0.082±0.006±0.005. Fits of the kinematic distributions provide parameters describing their form factors. Combining the form factor results with R0 gives |f+π(0)|2|Vcd|2/|f+K(0)|2|Vcs|2=0.038−0.007−0.003+0.006+0.005.