Time-Dependent CP Violation Effects in Partially Reconstructed $B^0 \to D^* \pi$ Decays

TL;DR

This paper measures time-dependent CP violation parameters in $B^0 o D^* o ext{pions}$ decays using partial reconstruction, providing insights into CP violation related to the angle $\

Contribution

It introduces a partial reconstruction method for analyzing CP violation in $B^0$ decays, improving measurement techniques with large data samples.

Findings

Measured CP violation parameters $S^+ = 0.035 \

Measured CP violation parameters $S^- = 0.025 \

Used 140 fb$^{-1}$ of data at Belle detector

Abstract

We report measurements of time-dependent decay rates for $B^0 \to D^{*\mp} \pi^\pm$ decays and extraction of CP violation parameters related to $\phi_3$. We use a partial reconstruction technique, whereby signal events are identified using information only from the primary pion and the charged pion from the decay of the $D^{*\mp}$. The analysis uses $140 {\rm fb}^{-1}$ of data accumulated at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. We measure the CP violation parameters $S^+ = 0.035 \pm 0.041 ({\rm stat}) \pm 0.018 ({\rm syst})$ and $S^- = 0.025 \pm 0.041 ({\rm stat}) \pm 0.018 ({\rm syst})$.