Comparison of D → K0Sπ and D → K0Lπ Decay Rates

We present measurements of D → K 0 S π and D → K 0 L π branching fractions using 281 pb -1 of ψ(3770) data at the CLEO-c experiment. We find that B(D 0 → K 0 S π 0 ) is larger than B(D 0 →K 0 L π 0 ), with an asymmetry of R(D°) = 0.108 ± 0.025 ± 0.024. For B(D + → K 0 S 7 + ) and B(D + → K 0 L π + ), we observe no measurable difference; the asymmetry is R(D + ) = 0.022 ± 0.016 ± 0.018. The D° asymmetry is consistent with the value based on the U-spin prediction A(D 0 → K 0 π 0 )/A(D 0 → K 0 π 0 ) =-tan 2 θ c , where θ c is the Cabibbo angle.