Experimental Study Of D⁺→K_S,L⁰K⁺（π⁰） At BESⅢ

Using 2.93 fb^-1 of electron-positron annihilation data collected at the ψ（3770）resonance with the BESIII detector on the BEPCII electron-positron storage,we mea-sure the branching fractions and related CP violation in D⁺ → K_S⁰K⁺,D⁺ →K_S⁰K⁺π⁰,D⁺ → K_L⁰K⁺ and D⁺ → K_L⁰K⁺π⁰.The results are:B（D⁺ → K_S⁰K⁺）=（3.06 ± 0.09 ± 0.08）× 10-3,B（D⁺ → K_L⁰K⁺）=（3.23 ± 0.11 ± 0.11）× 10-3,B（D⁺ → K_S⁰K⁺π⁰）=（5.16 ± 0.21 ± 0.23）× 10-3,B（D⁺ → K_L⁰K⁺π⁰）=（5.22 ± 0.22 ± 0.21）× 10-3.and A_CP^D→K_S⁰K=(^-1.5 ± 2.8 ± 1.6)%,A_CP^D→K_L⁰K=（-3.0 ± 3.2 ± 1.2）%,A_CP^D→K_S⁰Kπ⁰=（1.4 ± 4.0 ± 2.4）%,A_CP^D→K_L⁰Kπ⁰=（-0.9 ± 4.1 ± 1.6）%.The branching fraction for D⁺ → K_S⁰K⁺ is consistent with the PDG value,and the branching fractions for D⁺ → K_S⁰K⁺π⁰,D⁺ → K_L⁰K⁺ and D⁺ → K_L⁰K⁺π⁰ are measured for the first time.Beside of using branching fraction measurement,we al-so measure CP asymmetry by dividing region on Dalitz Plot for three^-body decays D⁺ → K_S,L⁰K⁺π⁰ and do not find evidence for CP violation.We perform an analysis of the D⁺ → K_S⁰K⁺π⁰ Dalitz plot using the same data sample.We test several sets with different contributing intermediate resonances,and find the Dalitz Plot is mainly represented by a combination of seven quasi-two-body decay channels（K*（892）⁺K_S⁰ K*（892）0K⁺,K*（1410）⁺K_S⁰ K*（1410）0K⁺,K₀^*（1430）⁺K_S⁰,K2*（1430）⁺K_S⁰,（?）2*（1430）0K⁺）plus a non-resonant component.Using the fit frac-tions from this analysis,relative branching ratios of each intermediate resonances are measured.Using double^-tag technique,we study ΔE systematic uncertainty of six charged and three neutral D meson decay modes,which value is about 0.1%level。...