Search for mixing-induced CP violation using partial reconstruction of B ¯ 0 →d∗+X- ν ¯ and kaon tagging SEARCH for MIXING-INDUCED CP VIOLATION ⋯ J. P. LEES et al

We describe in detail a previously published measurement of CP violation in B 0 - B ̄ 0 oscillations, based on an integrated luminosity of 425.7 fb −1 collected by the BABAR experiment at the PEPII collider. We apply a novel technique to a sample of about 6 million B ̄ 0 → D þ l − ν ̄ l decays selected with partial reconstruction of the D þ meson. The charged lepton identifies the flavor of one B meson at its decay time, the flavor of the other B is determined by kaon tagging. We determine a CP violating asymmetry A CP 1⁄4 ðNðB 0 B 0 Þ − Nð B ̄ 0 B ̄ 0 ÞÞ=ðNðB 0 B 0 Þ þ Nð B ̄ 0 B ̄ 0 ÞÞ 1⁄4 ð0.06 0.17 þ0.38 −0.32 Þ% corresponding to Δ CP 1⁄4 þ1.88−3 1 − jq=pj 1⁄4 ð0.29 0.84 −1.61 Þ × 10 . This measurement is consistent and competitive with those obtained at the B factories with dilepton events.