Evidence for the Rare Decay B+ --> Ds+ pi0

Abstract

We have searched for the rare decay B+ --> Ds+ pi0. The analysis is based on a sample of 232 million Upsilon(4S) --> B anti-B decays collected with the BABAR detector at the PEP-II e+ e- storage ring. We find 19.6 signal events, corresponding to a significance of 4.7 sigma. The extracted signal yield including statistical and systematic uncertainties is 20.1+6.8+0.4 -6.0-1.5, and we measure B(B+ --> Ds+ pi0) =(1.5 +0.5 -0.4 +- 0.1 +- 0.2) 10^-5, where the first uncertainty is statistical, the second is systematic, and the last is due to the uncertainty on the Ds+ decay and its daughter decay branching fractions.