First Observation of CP Violation in B^0 →D(*)_(CP)h^0 Decays by a Combined Time-Dependent Analysis of BABAR and Belle Data

We report a measurement of the time-dependent CP asymmetry of B^0 →D(*)_(CP)h^0 decays, where the light neutral hadron h^0 is a π^0, η, or ω meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K−, K^0_S π^0, or K^0_Sω. The measurement is performed combining the final data samples collected at the Υ(4S) resonance by the BABAR and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471±3)×10^6 BB pairs recorded by the BABAR detector and (772±11)×10^6 BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters –η_fS=+0.66±0.10(stat)±0.06(syst) and C=−0.02±0.07(stat)±0.03(syst). These results correspond to the first observation of CP violation in B^0 →D(*)_(CP)h^0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations. ; © 2015 American Physical Society. Received 14 May 2015; published 16 September 2015. We thank the PEP-II and KEKB groups for the excellent operation of the accelerators, and the computing organizations that support BABAR and Belle. The Belle experiment wishes to acknowledge the KEK cryogenics group for efficient solenoid operations. This work was supported by ARC and DIISR (Australia); FWF (Austria); NSERC (Canada); NSFC (China); MSMT (Czechia); CEA and CNRS-IN2P3 (France); BMBF, CZF, DFG, and VS (Germany); DST (India); INFN (Italy); MEXT, JSPS and Nagoya TLPRC (Japan); MOE, MSIP, NRF, GSDC of KISTI, and BK21Plus (Korea); FOM (The Netherlands); NFR (Norway); MNiSW and NCN (Poland); MES and RFAAE (Russian Federation); ARRS (Slovenia); IKERBASQUE, MINECO and UPV/EHU (Spain); SNSF (Switzerland); NSC and MOE (Taiwan); STFC (United Kingdom); BSF (USA-Israel); and DOE and NSF (USA). Individuals have received support from the Marie Curie EIF (European Union) and the A. P. Sloan Foundation (USA). ; Published - PhysRevLett.115.121604.pdf Submitted - 1505.04147v2.pdf