Study of CP Violating Effects in Time Dependent $B^0(\overline{B^0})\to D^{(\ast )\mp }{\pi }^{\pm }$ Decays

Abstract

We report measurements of time dependent decay rates for $B^0({\bar{B}}^0)\to D^{(\ast )\mp }{\pi }^{\pm }$ decays and extraction of CP violation parameters containing ${\varphi }_3$. Using fully reconstructed $D^{(\ast )}\pi$ events from a $140{\mathrm{fb}}^{-1}$ data sample collected at the ${\rm Y}(4S)$ resonance, we obtain the CP violation parameters for $D^{\ast }\pi$ and $D\pi$ decays, $2R_{D^{(\ast )}\pi }\sin (2{\varphi }_1+{\varphi }_3\pm {\delta }_{D^{(\ast )}\pi })$, where $R_{D^{(\ast )}\pi }$ is the ratio of the magnitudes of the doubly-Cabibbo-suppressed and Cabibbo-favoured amplitudes, and ${\delta }_{D^{(\ast )}\pi }$ is the strong phase difference between them. Under the assumption of ${\delta }_{D^{(\ast )}\pi }$ being close to either 0 or $180^{\circ }$, we obtain $|2R_{D^{\ast }\pi }\sin (2{\varphi }_1+{\varphi }_3)|=0.060\pm 0.040(\mathrm{stat})\pm 0.019(\mathrm{sys})$ and $|2R_{D\pi }\sin (2{\varphi }_1+{\varphi }_3)|=0.061\pm 0.037(\mathrm{stat})\pm 0.018(\mathrm{sys})$.

9 pages, 3 figures, Submitted to Physical Review Letters