Dalitz Plot Analysis of the $D^+\rightarrow K^0_S π^+ π^0$ Decay

Abstract: We perform an analysis of the $$D^+\rightarrow K^0_S \pi⁺ \pi<sup>0$$ Dalitz plot using a data set of 2.92 fb$<sup>{-1}$ of $e<sup>+e<sup>-$ collisions at the $\psi(3770)$ accumulated by the BESIII Experiment, in which 166694 candidate events are selected with a background of 15.1%. The Dalitz plot is found to be well-represented by a combination of six quasi-two-body decay channels ($K<sup>0_S\rho<sup>+$, $K<sup>0_S\rho(1450)<sup>+$, $\overline{K}<sup>{*0}\pi<sup>+$, $\overline{K}_0(1430)<sup>0\pi<sup>+$, $\overline{K}(1680)<sup>0\pi<sup>+$, $\overline{\kappa}<sup>0\pi<sup>+$) plus a small non-resonant component. We also consider a model-independent approach to confirm an obvious phase shift for the $\overline{\kappa}\pi$ component. Using the fit fractions from this analysis, partial branching ratios are updated with higher precision than previous measurements.