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

By using 1.8 × 10 6 DD pairs, we have measured B(D 0 → π - e + ν e ) = 0.299(11)(9)%, B(D + → π 0 e + ν e )= 0.373 (22)(13)%, B(D 0 → K - e + ν e ) = 3.56(3)(9)%, and B(D + → k 0 e + ,ν e ) = 8.53(13) × (23)% and have studied the q 2 dependence of the form factors. By combining our results with recent lattice calculations, we obtain |V cd | = 0.217(9)(4)(23) and |V cs | = 1.015(10)(11)(106).