Measurement of B(D+ → K̄*0l+νl)

Using 13.53 fb - 1 of CLEO data, we have measured the ratios of the branching fractions R + e , R + μ and the combined branching fraction ratio R + l , defined by R + l = [B(D + → K* 0 l + v l )]/[B(D + → K - π + π + )]. We find R + e = 0.74 ′ 0.04 ′ 0.05, R + μ = 0.72 ′ 0.10 ′ 0.05, and R + l = 0.74 ′ 0.04 ′ 0.05, where the first and second errors are statistical and systematic, respectively. The known branching fraction B(D + → K - π + π + ) leads to B(D + → K* 0 e + v e ) = (6.7 ′ 0.4 ′ 0.5 ′ 0.4)%, B(D + → k* 0 μ + v μ ) = (6.5 ′ 0.9 ′ 0.5 ′ 0.4)%, and B(D + → K* 0 l + v l ) = (6.7 ′ 0.4 ′ 0.5 ′ 0.4)%, where the third error is due to the uncertainty in B(D + → K - π + π + ).