Study of the semileptonic charm decays D0→π-e+νe, D+→π0e+νe, D0→K-e+νe, and D+→K̄0e+νe

Using a sample of 1.8 million DD̄ mesons collected at the ψ(3770) with the CLEO-c detector, we study the semileptonic decays D0→π-e+νe, D+→π0e+νe, D0→K-e+νe, and D+→K̄0e+νe. For the total branching fractions we find B(D0→π-e+νe)=0.299(11)(9)%, B(D+→π0e+νe)=0.373(22)(13)%, B(D0→K-e+νe)=3.56(3)(9)%, and B(D+→K̄0e+νe)=8.53(13)(23)%, where the first error is statistical and the second systematic. In addition, form factors are studied through fits to the partial branching fractions obtained in five q2 ranges. By combining our results with recent unquenched lattice calculations, we obtain |Vcd|=0.217(9)(4)(23) and |Vcs|=1.015(10)(11)(106), where the final error is theoretical.