Evidence for Charged B Meson Decays to a1±(1260)π0 and a10(1260)π±

We present measurements of the branching fractions for the decays B±→a1±(1260)π0 and B±→a10(1260)π± from a data sample of 232×106 BB̅ pairs produced in e+e- annihilation through the Υ(4S) resonance. We measure the branching fraction B(B±→a1±(1260)π0)×B(a1±(1260)→π-π+π±)=(13.2±2.7±2.1)×10-6 with a significance of 4.2σ, and the branching fraction B(B±→a10(1260)π±)×B(a10(1260)→π-π+π0)=(20.4±4.7±3.4)×10-6 with a significance of 3.8σ, where the first error quoted is statistical and the second is systematic.