  The exclusive semileptonic heavy baryon decay \Lambda_b\to p l\bar\nu is
investigated using light-cone sum rule method in both full QCD and 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 are typically one order smaller. Both results are consistent with the
experimental upper limit and can be compared to the refined experimental data
in the future.
