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

TL;DR

This study measures time-dependent decay rates of B mesons to extract CP violation parameters related to the CKM phase angles, providing insights into matter-antimatter asymmetry.

Contribution

It presents the first measurements of CP violation parameters in B to D(*)π decays using a large data sample, advancing understanding of CP violation in these channels.

Findings

Measured CP violation parameters with statistical and systematic uncertainties.

Provided constraints on the combination of CKM phases 2φ₁ + φ₃.

Results are consistent with Standard Model expectations.

Abstract

We report measurements of time dependent decay rates for $B^0(\bar{B}^0) \to D^{(*)\mp}\pi^{\pm}$ decays and extraction of CP violation parameters containing $\phi_3$. Using fully reconstructed $D^{(*)}\pi$ events from a $140 {\rm fb}^{-1}$ data sample collected at the $\Upsilon(4S)$ resonance, we obtain the CP violation parameters for $D^* \pi$ and $D \pi$ decays, $2R_{D^{(*)} \pi} \sin (2\phi_1 + \phi_3 \pm \delta_{D^{(*)} \pi})$, where $R_{D^{(*)} \pi}$ is the ratio of the magnitudes of the doubly-Cabibbo-suppressed and Cabibbo-favoured amplitudes, and $\delta_{D^{(*)} \pi}$ is the strong phase difference between them. Under the assumption of $\delta_{D^{(*)} \pi}$ being close to either 0 or $180^{\circ}$, we obtain $|2R_{D^* \pi} \sin (2\phi_1 + \phi_3)| = 0.060 \pm 0.040(\mathrm{stat}) \pm 0.019(\mathrm{sys})$ and $|2R_{D \pi} \sin (2\phi_1 + \phi_3)| = 0.061 \pm 0.037(\mathrm{stat}) \pm 0.018(\mathrm{sys})$.