Measurement of the B+- --> rho+- pi0 Branching Fraction and Direct CP Asymmetry

Abstract

An improved measurement of the process B+- --> rho+- pi0 is presented. The data sample of 211/fb comprises 232 million Y(4S) --> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. The yield and CP asymmetry are calculated using an extended maximum likelihood fitting method. The branching fraction and asymmetry are found to be BR(B+- --> rho+- pi0) = [10.0 +- 1.4 (stat) +- 0.9 (syst)]x 10^-6 and Acp(B+- --> rho+- pi0) = -0.01 +- 0.13 (stat) +- 0.02 (syst), superseding previous measurements. The statistical significance of the branching fraction is calculated to be 8.7sigma.

17 pages, 5 postscript figures, contributed to Lepton-Photon 2005