Combined CP violation measurements by the BABAR and Belle Collaborations

We present results of a recent joint analysis campaign by the BaBar and Belle experiments. The approach combines in single physics analyses the 1.1 inverse attobarn collected at the $\Upsilon (4S)$ resonance by the BaBar and Belle ex- periments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. A measurement of the $CP$ violation parameters sin(2β) and cos(2β) by a time-dependent Dalitz plot analysis of $B^0 \to D^{(*)}h^0$ decays with $D \to K^0_S \pi^+\pi^-$ decays is reported. The result is sin(2β) = 0.80 ± 0.14 ± 0.06 ± 0.03 and cos(2β) = 0.91 ± 0.22 ± 0.09 ± 0.07, where the first error is statistical, the second is the experimental systematic uncertainty, and the third is due to the uncertainty of the Dalitz plot amplitude model. First evidence for cos(2β) > 0 at the level of 3.7 standard deviations is obtained. The angle β of the CKM Unitarity Triangle is measured to be $\beta = (22.5 \pm 4.4 \pm 1.2 \pm 0.6)\degree$. The hypothesis of $\beta = 0\degree$ is ruled out at the level of 5.1 standard deviations, and CP violation is observed in $B^0 \to D^{(*)}h^0$ decays. The trigonometric multifold solution of $\frac{\pi}{2} - \beta = (68.1 \pm 0.7)\degree$ is excluded at the level of 7.3 standard deviations, and an ambiguity in the determination of the apex of the CKM Unitarity Triangle is resolved.