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

TL;DR

This study searches for semileptonic B decays to Lambda_c+ baryons using a large dataset, employing full B reconstruction to suppress backgrounds, and sets an upper limit on the decay's branching fraction ratio.

Contribution

It introduces a method to constrain the semileptonic decay rate of B mesons to Lambda_c+ baryons with a large data sample and improved background suppression.

Findings

Set a 90% CL upper limit of 3.5% on the branching fraction ratio.

Used full B meson reconstruction to reduce non-B backgrounds.

Corrected for B0 mixing effects in flavor determination.

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 %.