Measurement of the relative strong-phase difference between $D^0$ and $\overline{D^0} \to K^0_S\pi^+\pi^-$

We present the BES-III Collaboration preliminary results for a model independent measurement of the strong phase difference between $D^0$ and $\overline{D^0} \to K^0\pi^+\pi^-$, through a binned dalitz analysis. The BES-III $\psi (3770) $ dataset generates $D^0$ and $\overline{D^0}$ pairs in a quantum-correlated state, which gives information about the CP state of the $D^0$ decay, allowing for a model independent measurement. The strong phase difference parameters $c_i$ and $s_i$ are determined for each phase bin of the $D^0 \to K^0\pi^+\pi^-$ dalitz plot by measuring the population of CP and flavor states present. These results represent a significant statistical improvement in a previously statically limited measurement, which will allow for increased precision in the measurement of unitarity triangle angle $\gamma / \phi_3$ using the decay $B^\pm \to D(K^0_S \pi^+ \pi^-)K^\pm$ through the GGSZ method.