Improved measurements of D meson semileptonic decays to pi and K mesons

Using the entire CLEO-c ψ(3770)→DD̄ event sample, corresponding to an integrated luminosity of 818pb-1 and approximately 5.4×106 DD̄ events, we present a study of the decays D0→π-e+νe, D0→K-e+νe, D+→π0e+νe, and D+→K̄0e+νe. Via a tagged analysis technique, in which one D is fully reconstructed in a hadronic mode, partial rates for semileptonic decays by the other D are measured in several q2 bins. We fit these rates using several form factor parametrizations and report the results, including form factor shape parameters and the branching fractions B(D0→π-e+νe)=(0.288±0. 008±0.003)%, B(D0→K-e+νe)=(3.50±0.03±0.04)%, B(D+→π0e+νe)=(0.405±0.016±0.009)%, and B(D+→K̄0e+νe)=(8.83±0.10±0.20)%, where the first uncertainties are statistical and the second are systematic. Taking input from lattice quantum chromodynamics, we also find |Vcd|=0.234±0.007±0. 002±0.025 and |Vcs|=0.985±0.009±0.006±0.103, where the third uncertainties are from lattice quantum chromodynamics. © 2009 The American Physical Society.