Measurement of the hadronic structure of semileptonic D0 and D+ decays.
Absolute branching fractions for the {ital D}{sub {ital l}3} and {ital D}{sub {ital l}4} decays {ital D}{sup +}{r arrow}{ital {bar K}} {sup 0}{ital e+}{nu}{sub {ital e}}, {ital D}{sup +}{r arrow}{ital {bar K}} {sup 0}{mu}{sup +}{nu}{sub {mu}}, {ital D}{sup +}{r arrow}{ital {bar K}} {sup *0}{ital e+}{nu}{sub {ital e}}, and {ital D}{sup 0}{r arrow}{ital K}{sup *{minus}}{ital e+}{nu}{sub {ital e}} are determined using completely reconstructed {ital D{bar D}} events at the {psi}(3770). Reconstructed {ital D}{sup 0}{r arrow}{ital K}{sup {minus}}{ital e+}{nu}{sub {ital e}} decays are used to determine the pole mass of the {ital f}{sub 4}({ital q}{sup 2}) form factor. Resonant {ital K}{sup *} production dominates the process {ital D}{r arrow}{ital K}{pi}{ital e}{nu}; the {ital K}{sup *} polarization is measured. Limits on several Cabibbo-suppressed channels are evaluated. A global fit imposing isospin symmetry is performed to the measured exclusive and inclusive semileptonic {ital D}{sup 0} and {ital D}{sup +} branching fractions to obtain an improved set of branching fractions.