Calculation of the semileptonic decay width of the ${\Lambda }_b$ baryon

Abstract

We extend the approach based on the light-cone expansion and the heavy quark effective theory to the inclusive semileptonic decay of an unpolarized $b$-flavored hadron. It is applied to calculate the semileptonic decay width of the ${\Lambda }_b$ baryon and its ratio to that of the B meson. We obtain ${\Gamma }_{SL}({\Lambda }_b)=51\pm 9|V_{cb}{|}^2{ps}^{-1}$ and ${\Gamma }_{SL}({\Lambda }_b)/{\Gamma }_{SL}(B)=1.052\pm 0.006$. From the latter, the semileptonic branching fraction for ${\Lambda }_b$ is predicted to be $(8.7\pm 0.7)$.

Comments: 11 pages, REVTeX