A model-dependent amplitude analysis of the decay $B^0\rightarrow D(K^0_S\pi^+\pi^-) K^{ *0}$ is performed using proton-proton collision data corresponding to an integrated luminosity of 3.0fb$^{ -1}$, recorded at $\sqrt{ s}=7$ and $8 TeV$ by the LHCb experiment. The CP violation observables $x_{ \pm}$ and $y_{ \pm}$, sensitive to the CKM angle $\gamma$, are measured to be \begin{ eqnarray*} x_- &=& -0.15 \pm 0.14 \pm 0.03 \pm 0.01, y_- &=& 0.25 \pm 0.15 \pm 0.06 \pm 0.01, x_+ &=& 0.05 \pm 0.24 \pm 0.04 \pm 0.01, y_+ &=& -0.65^{ +0.24}_{ -0.23} \pm 0.08 \pm 0.01, \end{ eqnarray*} where the first uncertainties are statistical, the second systematic and the third arise from the uncertainty on the $D\rightarrow K^0_S \pi^+\pi^-$ amplitude model. These are the most precise measurements of these observables. They correspond to $\gamma=(80^{ +21}_{ -22})^{ \circ}$ and $r_{ B^0}=0.39\pm0.13$, where $r_{ B^0}$ is the magnitude of the ratio of the suppressed and favoured $B^0\rightarrow D K^+ \pi^-$ decay amplitudes, in a $K\pi$ mass region of $\pm50 MeV$ around the $K^*(892)^0$ mass and for an absolute value of the cosine of the $K^{ *0}$ decay angle larger than $0.4$.
Categories: hep-ex