We report a measurement of the CP violation parameter $\varphi_1$ obtained in a time-dependent analysis of $B^0\to\bar{ D}{ }^{ (*)0}h^0$ decays followed by $\bar{ D}{ }^0\to K_S^0\pi^+\pi^-$ decay. A model-independent measurement is performed using the binned Dalitz plot technique. The measured value is $\varphi_1 = 11.7^{ \circ}\pm7.8^{ \circ}({ \rm stat.})\pm 2.1^{ \circ}({ \rm syst.})$. Treating $\sin{ 2\varphi_1}$ and $\cos{ 2\varphi_1}$ as independent parameters, we obtain $\sin{ 2\varphi_1} = 0.43\pm 0.27({ \rm stat.})\pm 0.08({ \rm syst.})$ and $\cos{ 2\varphi_1} = 1.06\pm 0.33({ \rm stat.})^{ +0.21}_{ -0.15}({ \rm syst.})$. The results are obtained with a full data sample of $772 \times 10^6 B\bar{ B}$ pairs collected near the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.
Categories: hep-ex hep-ph