本项目拟利用北京谱仪Ⅲ采集的2.92 fb-1 ψ(3770) 数据样本，对粲介子衰变道D+ -> K+ K- π+ 和 D+ -> KS0 K+ π0进行达利兹图的分析研究。这两道都是单重Cabibbo压制的，通过达利兹图分析它们的中间共振态，不但可以研究相关的CKM矩阵元，而且能够揭示衰变过程的动力学机制，比如干涉效应、末态相互作用等，从而有效地检验重味介子衰变的夸克模型。此外，粲介子单重Cabibbo压制衰变道的CP破坏对新物理敏感，测量这些衰变过程的电荷不对称性是寻找新物理的独特途径。该项目的研究方法可以应用于粲介子的其他多体衰变过程，且不限于三体。

With this proposal, we are going to perform the Dalitz-plot analysis of the charmed-meson decay channels, D+ -> K+ K- π+ and D+ -> KS0 K+ π0, using a ψ(3770) sample of 2.92 fb-1 accumulated with the BESIII detector. Both of the channels are singly Cabibbo suppressed (SCS). Analyzing their intermediate resonances with Dalitz plot, not only we can study the relevant CKM elements, but also can explore the dynamics of the decays, including interference patterns, final state interactions and so on. Therefore it provides a powerful way to test the quark model of decays of heavy flavor mesons. In addition, CP violation in SCS decays of charm mesons is sensitive to new physics. Measurements of charge asymmetry of the decays is a unique way to search for new physics. The techniques developed within this proposal can be used to study other multi-body, not limited to three-body, decays of charm mesons.