Evidence for B semileptonic decays into the charmed baryon Lambda_c+

TL;DR

This paper provides the first evidence of B meson semileptonic decays into the Lambda_c+ baryon, using a large data set and a novel tagging method, with a measured relative branching fraction around 3%.

Contribution

It reports the first observation of B -> Lambda_c+ semileptonic decays and measures their relative branching fraction, advancing understanding of baryonic B decays.

Findings

First evidence for B -> Lambda_c+ semileptonic decays

Measured relative branching fraction approximately 3%

Signal significance of 4.9 standard deviations

Abstract

We present the first evidence for B semileptonic decays into 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. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We measure the relative branching fraction BF(Bbar -> Lambda_c+ X l- nubar_l)/BF(Bbar -> Lambda_c+/Lambda_c- X) = (3.2 +/- 0.9_stat +/- 0.9_syst)%. The significance of the signal including the systematic uncertainty is 4.9 standard deviations.