Time-dependent CP violation effects in partially reconstructed B0→D∗∓π± decays

Abstract We report measurements of time-dependent decay rates for B 0 → D ∗ ∓ π ± decays and extraction of CP violation parameters related to ϕ 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 ∗ ∓ . The analysis uses 140 fb −1 of data accumulated at the ϒ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. We measure the CP violation parameters S + = 0.035 ± 0.041 ( stat ) ± 0.018 ( syst ) and S − = 0.025 ± 0.041 ( stat ) ± 0.018 ( syst ) .