Study of Decay Dynamics and CP Asymmetry In D⁺ → K{_L^0} e⁺ν_e Decay

Using 2.92 fb⁻¹ of electron-positron annihilation data collected at √s̅ = 3.773 GeV with the BESIII detector, we obtain the first measurements of the absolute branching fraction B(D⁺ → K(L)⁰e⁺ν(e)) = (4.481 ± 0.027(stat) ± 0.103(sys))% and the CP asymmetry A(CP)^{D+ → K(L)⁰e⁺ν(e)} = (-0.59 ± 0.60(stat) ± 1.48(sys))%. From the D⁺ → K(L)⁰e⁺ν(e) differential decay rate distribution, the product of the hadronic form factor and the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element, f(+)^K (0) |V(cs)|. is determined to be 0.728 ± 0.006(stat) ± 0.011(sys). Using |V(cs)| from the SM constrained fit with the measured f(+)^K (0) |V(cs)|, f(+)^K(0) = 0.748 ± 0.007(stat) ± 0.012(sys) is obtained, and utilizing the unquenched Lattice QCD (LQCD) calculation for f(+)^K(0), |V(cs)| = 0.975 ± 0.008(stat) ± 0.015(sys) ± 0.025(LQCD).