The exclusive semileptonic heavy baryon decay ${\Lambda }_b\to p\mathcal{l}\overline{\nu }$ is investigated using the light-cone sum rule method in both full QCD and heavy quark effective theory (HQET). The form factors describing the decay are calculated and used to predict the decay width and differential distribution. The total decay width obtained from full QCD is in agreement with the previous theoretical predictions, while the HQET result is typically one order smaller. Both results are consistent with the experimental upper limit and can be compared to refined experimental data in the future.

• Received 12 January 2004

DOI:https://doi.org/10.1103/PhysRevD.69.094003