Measurement of cos 2β in B0→D(*)h0 Decays with a Time-Dependent Dalitz Plot Analysis of D→K0sπ+π−

Abstract

We study the time-dependent Dalitz plot of D → K 0 S π + π − in B 0 → D ( * ) h 0 decays, where h 0 is a π 0 , η , η ′ , or ω meson and D ∗ → D π 0 , using a data sample of 383 × 10 6 Υ ( 4 S ) → B ¯¯¯ B decays collected with the BABAR detector. We determine cos  2 β = 0.42 ± 0.49 ± 0.09 ± 0.13 , sin  2 β = 0.29 ± 0.34 ± 0.03 ± 0.05 , and | λ | = 1.01 ± 0.08 ± 0.02 , where the first error is statistical, the second is the experimental systematic uncertainty, and the third, where given, is the Dalitz model uncertainty. Assuming the world average value for sin  2 β and | λ | = 1 , cos  2 β > 0 is preferred over cos  2 β < 0 at 86% confidence level.