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Title: Measurement of branching fraction and first evidence of CP violation in B⁰→a₁±(1260)π decays

We present a measurement of the branching fraction and time-dependent CP violation parameters in B⁰→a±₁(1260)π decays. The results are obtained from the final data sample containing 772×10⁶ BB¯¯¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e⁻ collider. We obtain the product branching fraction B(B⁰→a±₁(1260)π)×B(a±₁(1260)→π±ππ±)=(11.1±1.0(stat)±1.4(syst))×10⁻⁶ and an upper limit on the product branching fraction for a possible decay with the same final state B(B⁰→a±₂(1320)π)×B(a±₂(1320)→π±ππ±)<2.2×10⁻⁶at 90% CL. In a time-dependent measurement to extract CP asymmetries, we obtain the CP violation parameters ACP=–0.06±0.05(stat)±0.07(syst), CCP=–0.01±0.11(stat)±0.09(syst), SCP=–0.51±0.14(stat)±0.08(syst), representing time- and flavor-integrated direct, flavor-dependent direct and mixing-induced CP violation, respectively. Simultaneously, we also extract the CP-conserving parameters ΔC=+0.54±0.11(stat)±0.07(syst), ΔS=–0.09±0.14(stat)±0.06(syst), which, respectively, describe a rate difference and strong phase difference between the decay channels where the a±₁ does not contain the spectator quark and those where it does. We find first evidence of mixing-induced CP violation in B⁰→a±₁(1260)π decays with 3.1σ significance. The rate where the a±₁ does not contain the spectator quark from the B meson is found to dominate the rate where it does at the 4.1σ level. However, there is no evidence for either time- and flavor-integrated direct CP violation or flavor-dependent direct CP violation.
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Publication Date:
OSTI Identifier:
1101822
Type:
Publisher's Accepted Manuscript
Journal Name:
Physical Review. D, Particles, Fields, Gravitation and Cosmology
Additional Journal Information:
Journal Volume: 86; Journal Issue: 9; Journal ID: ISSN 1550-7998
Publisher:
American Physical Society
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English