Search for Bbar --> Lambda_c+ X l- nu Decays in Events With a Fully Reconstructed B Meson

Abstract

We present a search for semileptonic B decays to the charmed baryon Lambda_c+ based on 420 fb-1 of data collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II $e^+e^-$ storage rings. By fully reconstructing the recoiling B in a hadronic decay mode, we reduce non-B backgrounds and determine the flavor of the signal B. We statistically correct the flavor for the effect of the B0 mixing. We obtain a 90% confidence level upper limit of BF(Bbar --> Lambda_c+ X l- nubar)/BF(Bbar --> Lambda_c+ X) < 3.5 %.