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 B-0 -> a(1)(+/-)(1260)pi(-/+) decays. The results are obtained from the final data sample containing 772 x 10(6) B (B) over bar pairs collected at the Gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We obtain the product branching fraction B(B-0 -> a(1)(+/-)(1260)pi(-/+)) x B(a(1)(+/-)(1260) -> pi(+/-)pi(-/+)pi(+/-)) = (11.1 +/- 1.0(stat) +/- 1.4(syst)) x 10(-6) and an upper limit on the product branching fraction for a possible decay with the same final state B(B-0 -> a(2)(+/-)(1320)pi(-/+)) x B(a(2)(+/-)(1320) -> pi(+/-)pi(-/+)pi(+/-)) a(1)(+/-)(1260)pi(-/+) decays with 3.1 sigma significance. The rate where the a(1)(+/-) 1 does not contain the spectator quark from the B meson is found to dominate the rate where it does at the 4.1 sigma level. However, there is no evidence for either time-and flavor-integrated direct CP violation or flavor-dependent direct CP violation.