Search for the rare decay B to pi l+ l-

Abstract

We have performed a search for the flavor-changing neutral-current decays B --> pi l+l-, where l+l- is either e+e- or mu+mu-, using a sample of 230 million Y(4S)-->BBbar decays collected with the BABAR detector. We observe no evidence of a signal and measure the upper limit on the isospin-averaged branching fraction to be BF(B --> pi l+ l-) < 9.1 x 10^{-8} at 90% confidence level. We also search for the lepton-flavor--violating decays B --> pi e mu and measure an upper limit on the isospin-averaged branching fraction of BF(B --> pi e mu) < 9.2 x 10^{-8} at 90% confidence level.