Measurement of branching fractions of B decays to K(1)(1270)pi and K(1)(1400)pi and determination of the CKM angle alpha from B(0) -> a(1)(1260)(+/-)pi(-/+) RID C-5223-2009

We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K(1)(1270) or K(1)(1400) meson and a charged pion. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, correspond to 454 x 10(6) B (B) over bar pairs produced in e(+)e(-) annihilation. We measure the branching fractions B(B(0) -> K(1)(1270)(+)pi(-) + K(1)(1400)(+)pi(-)) = 3.1(-0.7)(+0.8) x 10(-5) and B(B(+) -> K(1)(1270)(0)pi(+) + K1(1400)(0)pi(+)) = 2.9(-1.7)(+2.9) x 10(-5) (< 8.2 x 10(-5) at 90% confidence level), where the errors are statistical and systematic combined. The B(0) decay mode is observed with a significance of 7.5 sigma, while a significance of 3.2 sigma is obtained for the B(+) decay mode. Based on these results, we estimate the weak phase alpha = (79 +/- 7 +/- 11)degrees from the time-dependent CP asymmetries in B(0) -> a(1)(1260)(+/-)pi(-/+) decays.